rus
Issue #1/2018
V. P. Lopasov, I. V. Ivonin
Generation of a new-type laser radiation for solving knowledge-based applied problems. Part 1
Generation of a new-type laser radiation for solving knowledge-based applied problems. Part 1
A physical basis for the generation of magnetomultipole (MM) radiation in the wavelength range 250–900 nm in the "set of fields + molecular gas" non-equilibrium system is created. The mechanism of the two-dimensional feedback between the energies of the quadratic Stark effect at the low-frequency electric dipole (starter) and the Zeeman effect at the high-frequency magnetic multipole (working) vibrational-rotational (VR) transitions is substantiated.
Теги: magnetomultipolar laser propagation of laser radiation in the atmosphere магнитомультипольный лазер распространение лазерного излучения в атмосфере
1. INTRODUCTION.
Traditional representation of the laser radiation generation is based on the physics of a laser consisting of three elements: working medium, resonator and pumping system. Characteristics of these elements are described separately, and interaction of the pumping field with the medium in the laser resonator is described in the frameworks of the quantum-electrodynamic (QED) approach to the interaction of the electromagnetic (e/m) radiation with the matter [1, 2]. The physical basis in the frameworks of which the feedback (FB) in the resonator between the stimulated radiation at the working transition frequency and the molecules (atoms) of the active medium is launched, plays a key role. Generation is self-excited at the time moment when the threshold inversion of population has been reached between the states of the electrodipole (ED) transition of the medium at the frequency of one of the modes of the resonator. Each characteristic of the ED radiation is formed independently.
Last years, laser physics was added by new branches: fiber lasers [3], powerful lasers on thin discs shaped like cylindrical rods [4], quantum-cascade lasers, where the active medium is based on three coupled quantum wells [5], a supergrid [6] or a chipped supergrid [7]. In all aforementioned cases, generation of laser radiation is self-excited on the natural ED transitions of molecules (atoms) in the prepared active medium [1]. Such laser radiation has an electrodipole nature, coherence of the first order [8], and its propagation in the atmosphere depends on the Coulomb law, which favors increase of low- and high-frequency fluctuations of radiation in the medium.
The disadvantage of ED radiation is that its propagation in the atmosphere depends strongly on its aerosol-molecular-ion composition, including clouds, haze, fog, rain, snow (they reduce the signal-to-noise ratio of the laser channel). At the same time, turbulence of the atmosphere distorts the wave front of radiation up to destruction due to low- and high-frequency fluctuations of the intensity. Noise immunity of laser communication and navigation systems, and other tools in the atmosphere based on ED radiation is insufficient for the paths exceeding 1–5 km [9–12].
Solution of the knowledge-based communication, aerospace, atmospheric-optical and other problems requires a qualitatively new level of stability of the wavefront of laser radiation on long atmospheric paths, including with large magnetic induction in various objects. The development of a new depth of knowledge of the interaction of e/m radiation with matter for the generation of magnetomultipole (MM) radiation at the prepared MM electronic transition has become topical [13]. All characteristics of the MM radiation are formed interdependently.
The probability of MM transition of the aerosol-molecular-ion composition of the atmosphere is 7–8 orders of magnitude lower than the probability of ED transitions, and MM radiation in the atmosphere will be reduced as much less. In addition, in this case the Biot-Savart law plays a key role in formation of the complex refractive index of the medium. This law favors minimization of the low- and high-frequency fluctuations of the signal during the self-organization of the "collective of fields + molecular gas" system ("CF + MG") into an optically active ensemble of diamagnetic electron-ion nanoparticles.
A new representation of laser radiation is based on the physics of laser consisting of two elements: molecular gas and biharmonic pumping radiation (BR). The key characteristics of these elements are described in the frameworks of the quantum-electromagnetodynamic (QEMD) approach to the interaction of e/m radiation with matter [13, 14]. Generation of MM radiation is formed at a stage of ≈10–12, which is less than the duration of the elastic collision of molecules. Generation of the MM radiation is self-excited in the ensemble of electron-ion nanoparticles at the moment of accumulation of the threshold diamagnetic energy on the highly excited state of the prepared MM electronic transition.
The purpose of the paper is to create a physical basis for the generation of MM radiation with coherence of high order, a screw front, a large orbital magnetic/mechanical moment at the frequency of the prepared MM electronic transition at a given rate of accumulation of the threshold diamagnetic energy.
2. ANOMALOUS EXPERIMENTAL RESULTS IN LASER SPECTROSCOPY
2.1. Anomalous result of Н2О spectra in the ruby laser radiation field
In 1969, a group of laser spectroscopy at the IAO SB RAS developed, produced and put into operation a high-speed spectrometer based on a ruby laser with a thermal and electro-optical tuning of the radiation wavelength. The multi-path gas chamber with the White optical system made it possible to obtain the laser beam path length up to ℓ ≈ 300 at the distance between the mirrors ~5.0 m.
The laser generated BR: two frequencies of a width ≤300 MHz spaced apart by an interval ≈300 MHz at a tenfold intensity ratio I1 / I2 ≈ 1 / 10. The step of tuning the laser radiation frequency is limited from below by the intermode interval, and from above by the homogeneous width of the of the medium spectral line contour.
In 1970, the parameters of the known line of Н2О at 694.38 nm [15] were measured with a laser spectrometer at saturated water vapor Н2О in N2. Generation of the ruby laser was used at the repetition rate ≈5 МГц of double pulse peaks with the width ≤300 MHz of the spectrum of radiation with the linear (π) polarization. The absorption line of 694.38 nm corresponds to the degenerated SW transition 4–3 → 54 of the band 000 → 003 of the principal electronic state of the Н2О molecule.
The absorption of pumping radiation in Н2О was recorded at a sensitivity of Kλ,min ≈10–5 cm–1 in the frameworks of the Bouguer’s law for a more intense line of pumping BR with p-polarization with an error of 8–10% [16]. The ratio of the intensity of the beam leaving the chamber to its intensity at the input to the chamber was measured K = Jν / J0ν, Fig. 1.
In addition to the known absorption line of the H2O molecule at 694.38 nm, nine other weak lines were recorded. An anomaly was detected: the width of the known absorption line is approximately twice less than the width of the collisional contour. The absorption coefficient Кl in the center of the contour was approximately twice greater than the data [15]. Some of the nine lines were recorded in 2006 by means of the optical-acoustic spectrometer (OAC) [17].
In 1973, a powerful monochromatic reradiation signal near the absorption-line center was detected by means of a polychromatic intracavity laser spectrometer (ICLS) in the "laydown" of the ruby laser radiation from the H2O absorption line at 694.38 nm [15], Fig. 2. The result was published in a review paper [18].
The functional relation between the anomalous absorption/reradiation of light by H2O molecules in the line contour of 694.38 nm and the structure of pumping BR with π-polarization was revealed by means of two control experiments.
2.2 Results of control experimental measurements
The dependence of the H2O absorption line contour of 694,38 nm in N2 on the intensity It of quasi-monochromatic (0.03 cm‑1) ruby laser radiation at π and circular (σ) polarization was studied in the first control experiment at OAS [18].
The absorption of radiation of s-polarization (b) in the line center 694,38 nm was not changed at the intensity of 5–35 MW/cm2, while the intensity of radiation of p-polarization (a) in the line center decreased, Fig. 3.
The value А (It, λ) is the OAS signal under conditions of quasi-stationary 30–40 nm non-linear absorption. Narrowing of the absorption line contour
At the increase of the intensity in the range It ≈ 20–35 MW/cm2 was revealed. Here T and χ(λ) are the measurement time (0.5–1 hour) of the contour and the true contour of the absorption line.
Such a measurement Α(Ιt, λ) cannot be caused by the specific manner of the optical-acoustic method of measuring absorption at big intensities of the exciting radiation [19]. One can assume the presence of the effects related with the change of intra- and inter-molecular interaction in a strong light field [20].
The absorption saturation intensity Is derived from the dependence Α(Ιt, λ) in the absorption line center using the technique [19] for the total pressure of the mixture PH20+N2 ≈ 270 Torr takes the value (3,2±0,5) J/cm2. It is almost one order of magnitude greater than the value calculated from the dipole moment at the transition under study 4–3 → 54 of the band 000 → 003 of the H2O molecule.
One consider the following effect among that explaining narrowing the molecule line contour 694,38 nm in the strong field It ≈ 35 MW/cm2 at PH20+N2 ≈ 300 Torr.
1. Narrowing the molecular absorption line contour in the strong field due to transformation of the rotational levels of H2O [20].
The width of the line of composite vibrational-rotational (VR) transitions of the molecule H2O has a high sensitivity to a change in its polarizability in an external field [18].
2. Intensification of the Dicke effect (narrowing the collisional line contour) can intensify under "non-equilibrium" conditions of the medium because of the phase effect [22].
The phase effect appears at increasing correlation between the width, shift of levels and the probability of the molecular transition. The correlation increases because of the contribution of elastic collisions into the change of projections of the angular moments Ji, Jj of the transition levels at participation of the Stark splitting-displacement of the transition levels.
The estimates show that the time required for the contribution of elastic collisions into narrowing of the line contour should be less than the molecular free path time ≈10–10 s under conditions of the real atmosphere.
The second experiment consisted in detecting the influence of the resonant Stark splitting-displacement of the rotational levels of the Н2O absorption spectrum by the radio frequency (RF) field on the change in the line contour of the VR transition at its resonance to the optical radiation [24].
The Н2O molecule has the constant dipole moment ~2D and the complicated structure of the rotational levels divided into the intervals ΔωΒ ≈ 1 cm–1. The Stark splitting of VR levels is Δωst ≈ (d0 E0 / ħ)2 /ΔωB, where d0 is the dipole moment at a virtual transition from the working to the nearest excited level. At d0 ≈ 10–4 D, E0 ≈ 300 V/cm and ΔωB ≈ 1 cm–1 the split value is Δωst ≤ 1 МHz.
The effect of the RF field is reduced to equalizing the populations of the magnetic M- sublevels and to correlation ("spectral exchange") between the optical transitions JmMm ↔ JnMn due to the electric dipole moment induced by the elastic collision of Н2O and N2.
Participation of an elastic collision of molecules Н2O and N2 changes the absorption line contour of the VR transition K(ω) in the optical field. The simplest addition of the frequencies of the optical ω and alternating electric Ω fields in a three-level diagram including, for example, the levels Jm0, Jm1, and Jn0 (Fig.4) is realized as an optical-radio frequency resonance [25, 26].
Considering formulas (3.14)–(3.16) from [26] and the presence of RF field, we obtain the measure of the change of the line contour K (ω) of VR transition η ≈ (d0 E0 / ħ γ)2 ~ 1 at Δωst ≤ γ. That means, the change of the frequency Ω within the limits of the impact half-width of the optical transition γ ≤ 109 s–1 (the gas pressure ~50–200 Тоrr) can both broaden and narrow the line contour K (ω) in comparison with the case when the RF field E0 = 0.
The experiment was carried out with ICLS (the resonator length was ℓ = 9,6, the intermode interval was 15 MHz) with a dynamic Stark cell in a semi-confocal resonator of a ruby laser (the interval between the transverse modes was several units of MHz). The amplitude of electric field at the cell capacitor plates in ICLS varied within the limits 50–300 V/cm. The frequency Ω changed in the range 1–20 MHz characteristic of the repetition rate of the free energy peaks of the laser [16] and the intermode interval of the semi-confocal resonator of the laser [24]. The result of the experiment and the diagrams of the ICLS are shown in Fig. 5.
In the field of 300 V/cm, the maximum increase of γf and the decrease of I(0) are reached at the frequency of Ωy = 5 MHz, and the maximum decrease of γf and increase of I(0) are reached at the frequency of Ωc = 15 MHz. the change of the sign of deformation of the "laydown" contour occurs at the frequency of ΩH = 8,1 MHz. the results of measuring I(0) and γf is 10–15% at the errors in the values of the measured values 4%. The dependence of the "neutral" frequency on the field amplitude is quadratic, that proves the possibility of the control of narrowing the contour of the absorption/reradiation line in the anomalous range by means of the structure of the external e/m field.
2.3. Launch of the self-organization mechanism of nanoparticles in molecules Н2O
The analysis of experimental results and the result of research in 2000–2002 led to an idea of two-dimensional resonance in energy. The two-dimensional resonance is self-organized between the difference 2ω–q = (ω1q – ω2q), the sum 2ω+q = (ω1q + ω2q) of the BR pumping frequencies and the low-frequency k’ → k (starting) ED, high-frequency magnetic multipole (work) k →← n VR transitions. The VR transitions are combined by a lower state k into a V diagram, Fig. 6.
The two-dimensional resonance launches the mechanism of two-dimensional (in space and time) feedback between the energies of the quadratic Stark δWSt⊥∥q = 0 and δW˘Z⊥∥q = 0 Zeeman effects at the extreme conditions for the "CF+MG" system. Here q = 0, 1, 2, 3,...q* = 2ω+q=0 / 2ω–q=0 = 103–106 is the integer number of the step T+q / 4 of the effect of the collective of fields EΣ⊥∥q and HΣ∥⊥q on each molecule.
The collective of fields [13, 14] consists of the vector sum of the electric DC⊥∥q + EB⊥q + DR⊥q + EΣ⊥∥q and the vector sum of magnetic BC∥⊥q + HB∥q + BR∥q + HΣ∥⊥q components of the elastic collision field (C) of molecules with the broadening molecules, pumping BR with p-polarization (B) and the Rayleigh scattering (R). The molecular gas is the working molecules Н2O (mD) and the broadening molecules N2 (mb).
In this case the molecules Н2O in the coherence volume of BR
ΔVq=0 → ΔVq* ≈ Δz∥q*πr2nf⊥q*, (1)
existing in the state k’ participate in the open self-organization of the "CF + MG" system into an optically active ensemble of diamagnetic electron-ion nanoparticles at the MM electron transition prepared in the range of the magnetic multipole k →← n VR transition. Here Δz∥q* and πr2nf⊥q* are the time coherence length and the pumping BR radius, respectively.
The two-dimensional feedback mechanism is realized between the energies of the quadratic Stark δWSt⊥∥q = 0 and δW˘Z⊥∥q = 0 Zeeman effects at the critical conditions for the "CF+MG" system [13, 14].
2ω–q; 2ω+q; I1q / I2q ≠ 1; mb >> Nph >> mD; T°K (2)
The initial Stark δWSt⊥∥q = 0 and Zeeman δW˘Z⊥∥q = 0 energies at the step T+q / 4 provide the increase of fluctuations of the diamagnetic energy up to the threshold value δW˘Z⊥∥q* at the given asymmetry of intensities I1q=0 / I2q=0 ≠ 1; Nph – in the concentration of photons in the volume (1).
Elastic collision of N2 and Н2O induces in Н2O the electric (3)
de⊥∥q = α⊥∥q DC⊥∥q + 1/3 A⊥∥q ∇ DC⊥∥q + G⊥∥q BC⊥∥q ... (3)
and magnetic (4)
dm⊥∥q = –χd∥⊥q ΒC∥⊥q – ~G∥⊥q DC⊥∥q ... (4)
dipole moments [27] with polarizability α⊥∥q, diamagnetic susceptibility –χd∥⊥q, quadrupole polarizability 1/3 A⊥∥γq ∇ D∥γq and tensors G⊥∥q, ~G∥⊥q. The tensors G⊥∥q, ~G∥⊥q are functionally related with the gyration tensor gq of the molecule Н2O.
Iin the range of the ruby laser radiation, we use the V-diagram in the molecule Н2O consisting of two VR transitions
4–3q (000) → 4Е–3k (000) ←→ 5Е–4q (000) (5)
with the common lowest state 4–3q (000).
The state 4–3q (000) of the molecule Н2O is the result of displacement by 2∆JK ≈ 345.6 due to the centrifugal extension [28] and by 2∆JKq due to the elastic collision of Н2O with N2. The state 5Е–4q (000) is the result of displacement due to the collision. Here (000) ⇔ (103) is the vibrational transition of the molecule Н2O and J=4, 5 are the quantum numbers of the angular moment Н2O.
The authors thanks S. N. Bagaev for discussion of the result of the work at the Academic Council of the Institute of Laser Physics SB RAS and S. M. Kobtsev for a discussion of the results of the work, V. G. Bagrov and A. A. Rukhadze for consultations and useful discussions, V. N. Cherepanov and R. R. Valiev for the analytics of the "field collective + molecular gas" system.
The work was supported by the Skolkovo Foundation No. KTIT‑11 on 18.09.2012 and TRINC of the Tomsk Region in 2014.
to be continued
Traditional representation of the laser radiation generation is based on the physics of a laser consisting of three elements: working medium, resonator and pumping system. Characteristics of these elements are described separately, and interaction of the pumping field with the medium in the laser resonator is described in the frameworks of the quantum-electrodynamic (QED) approach to the interaction of the electromagnetic (e/m) radiation with the matter [1, 2]. The physical basis in the frameworks of which the feedback (FB) in the resonator between the stimulated radiation at the working transition frequency and the molecules (atoms) of the active medium is launched, plays a key role. Generation is self-excited at the time moment when the threshold inversion of population has been reached between the states of the electrodipole (ED) transition of the medium at the frequency of one of the modes of the resonator. Each characteristic of the ED radiation is formed independently.
Last years, laser physics was added by new branches: fiber lasers [3], powerful lasers on thin discs shaped like cylindrical rods [4], quantum-cascade lasers, where the active medium is based on three coupled quantum wells [5], a supergrid [6] or a chipped supergrid [7]. In all aforementioned cases, generation of laser radiation is self-excited on the natural ED transitions of molecules (atoms) in the prepared active medium [1]. Such laser radiation has an electrodipole nature, coherence of the first order [8], and its propagation in the atmosphere depends on the Coulomb law, which favors increase of low- and high-frequency fluctuations of radiation in the medium.
The disadvantage of ED radiation is that its propagation in the atmosphere depends strongly on its aerosol-molecular-ion composition, including clouds, haze, fog, rain, snow (they reduce the signal-to-noise ratio of the laser channel). At the same time, turbulence of the atmosphere distorts the wave front of radiation up to destruction due to low- and high-frequency fluctuations of the intensity. Noise immunity of laser communication and navigation systems, and other tools in the atmosphere based on ED radiation is insufficient for the paths exceeding 1–5 km [9–12].
Solution of the knowledge-based communication, aerospace, atmospheric-optical and other problems requires a qualitatively new level of stability of the wavefront of laser radiation on long atmospheric paths, including with large magnetic induction in various objects. The development of a new depth of knowledge of the interaction of e/m radiation with matter for the generation of magnetomultipole (MM) radiation at the prepared MM electronic transition has become topical [13]. All characteristics of the MM radiation are formed interdependently.
The probability of MM transition of the aerosol-molecular-ion composition of the atmosphere is 7–8 orders of magnitude lower than the probability of ED transitions, and MM radiation in the atmosphere will be reduced as much less. In addition, in this case the Biot-Savart law plays a key role in formation of the complex refractive index of the medium. This law favors minimization of the low- and high-frequency fluctuations of the signal during the self-organization of the "collective of fields + molecular gas" system ("CF + MG") into an optically active ensemble of diamagnetic electron-ion nanoparticles.
A new representation of laser radiation is based on the physics of laser consisting of two elements: molecular gas and biharmonic pumping radiation (BR). The key characteristics of these elements are described in the frameworks of the quantum-electromagnetodynamic (QEMD) approach to the interaction of e/m radiation with matter [13, 14]. Generation of MM radiation is formed at a stage of ≈10–12, which is less than the duration of the elastic collision of molecules. Generation of the MM radiation is self-excited in the ensemble of electron-ion nanoparticles at the moment of accumulation of the threshold diamagnetic energy on the highly excited state of the prepared MM electronic transition.
The purpose of the paper is to create a physical basis for the generation of MM radiation with coherence of high order, a screw front, a large orbital magnetic/mechanical moment at the frequency of the prepared MM electronic transition at a given rate of accumulation of the threshold diamagnetic energy.
2. ANOMALOUS EXPERIMENTAL RESULTS IN LASER SPECTROSCOPY
2.1. Anomalous result of Н2О spectra in the ruby laser radiation field
In 1969, a group of laser spectroscopy at the IAO SB RAS developed, produced and put into operation a high-speed spectrometer based on a ruby laser with a thermal and electro-optical tuning of the radiation wavelength. The multi-path gas chamber with the White optical system made it possible to obtain the laser beam path length up to ℓ ≈ 300 at the distance between the mirrors ~5.0 m.
The laser generated BR: two frequencies of a width ≤300 MHz spaced apart by an interval ≈300 MHz at a tenfold intensity ratio I1 / I2 ≈ 1 / 10. The step of tuning the laser radiation frequency is limited from below by the intermode interval, and from above by the homogeneous width of the of the medium spectral line contour.
In 1970, the parameters of the known line of Н2О at 694.38 nm [15] were measured with a laser spectrometer at saturated water vapor Н2О in N2. Generation of the ruby laser was used at the repetition rate ≈5 МГц of double pulse peaks with the width ≤300 MHz of the spectrum of radiation with the linear (π) polarization. The absorption line of 694.38 nm corresponds to the degenerated SW transition 4–3 → 54 of the band 000 → 003 of the principal electronic state of the Н2О molecule.
The absorption of pumping radiation in Н2О was recorded at a sensitivity of Kλ,min ≈10–5 cm–1 in the frameworks of the Bouguer’s law for a more intense line of pumping BR with p-polarization with an error of 8–10% [16]. The ratio of the intensity of the beam leaving the chamber to its intensity at the input to the chamber was measured K = Jν / J0ν, Fig. 1.
In addition to the known absorption line of the H2O molecule at 694.38 nm, nine other weak lines were recorded. An anomaly was detected: the width of the known absorption line is approximately twice less than the width of the collisional contour. The absorption coefficient Кl in the center of the contour was approximately twice greater than the data [15]. Some of the nine lines were recorded in 2006 by means of the optical-acoustic spectrometer (OAC) [17].
In 1973, a powerful monochromatic reradiation signal near the absorption-line center was detected by means of a polychromatic intracavity laser spectrometer (ICLS) in the "laydown" of the ruby laser radiation from the H2O absorption line at 694.38 nm [15], Fig. 2. The result was published in a review paper [18].
The functional relation between the anomalous absorption/reradiation of light by H2O molecules in the line contour of 694.38 nm and the structure of pumping BR with π-polarization was revealed by means of two control experiments.
2.2 Results of control experimental measurements
The dependence of the H2O absorption line contour of 694,38 nm in N2 on the intensity It of quasi-monochromatic (0.03 cm‑1) ruby laser radiation at π and circular (σ) polarization was studied in the first control experiment at OAS [18].
The absorption of radiation of s-polarization (b) in the line center 694,38 nm was not changed at the intensity of 5–35 MW/cm2, while the intensity of radiation of p-polarization (a) in the line center decreased, Fig. 3.
The value А (It, λ) is the OAS signal under conditions of quasi-stationary 30–40 nm non-linear absorption. Narrowing of the absorption line contour
At the increase of the intensity in the range It ≈ 20–35 MW/cm2 was revealed. Here T and χ(λ) are the measurement time (0.5–1 hour) of the contour and the true contour of the absorption line.
Such a measurement Α(Ιt, λ) cannot be caused by the specific manner of the optical-acoustic method of measuring absorption at big intensities of the exciting radiation [19]. One can assume the presence of the effects related with the change of intra- and inter-molecular interaction in a strong light field [20].
The absorption saturation intensity Is derived from the dependence Α(Ιt, λ) in the absorption line center using the technique [19] for the total pressure of the mixture PH20+N2 ≈ 270 Torr takes the value (3,2±0,5) J/cm2. It is almost one order of magnitude greater than the value calculated from the dipole moment at the transition under study 4–3 → 54 of the band 000 → 003 of the H2O molecule.
One consider the following effect among that explaining narrowing the molecule line contour 694,38 nm in the strong field It ≈ 35 MW/cm2 at PH20+N2 ≈ 300 Torr.
1. Narrowing the molecular absorption line contour in the strong field due to transformation of the rotational levels of H2O [20].
The width of the line of composite vibrational-rotational (VR) transitions of the molecule H2O has a high sensitivity to a change in its polarizability in an external field [18].
2. Intensification of the Dicke effect (narrowing the collisional line contour) can intensify under "non-equilibrium" conditions of the medium because of the phase effect [22].
The phase effect appears at increasing correlation between the width, shift of levels and the probability of the molecular transition. The correlation increases because of the contribution of elastic collisions into the change of projections of the angular moments Ji, Jj of the transition levels at participation of the Stark splitting-displacement of the transition levels.
The estimates show that the time required for the contribution of elastic collisions into narrowing of the line contour should be less than the molecular free path time ≈10–10 s under conditions of the real atmosphere.
The second experiment consisted in detecting the influence of the resonant Stark splitting-displacement of the rotational levels of the Н2O absorption spectrum by the radio frequency (RF) field on the change in the line contour of the VR transition at its resonance to the optical radiation [24].
The Н2O molecule has the constant dipole moment ~2D and the complicated structure of the rotational levels divided into the intervals ΔωΒ ≈ 1 cm–1. The Stark splitting of VR levels is Δωst ≈ (d0 E0 / ħ)2 /ΔωB, where d0 is the dipole moment at a virtual transition from the working to the nearest excited level. At d0 ≈ 10–4 D, E0 ≈ 300 V/cm and ΔωB ≈ 1 cm–1 the split value is Δωst ≤ 1 МHz.
The effect of the RF field is reduced to equalizing the populations of the magnetic M- sublevels and to correlation ("spectral exchange") between the optical transitions JmMm ↔ JnMn due to the electric dipole moment induced by the elastic collision of Н2O and N2.
Participation of an elastic collision of molecules Н2O and N2 changes the absorption line contour of the VR transition K(ω) in the optical field. The simplest addition of the frequencies of the optical ω and alternating electric Ω fields in a three-level diagram including, for example, the levels Jm0, Jm1, and Jn0 (Fig.4) is realized as an optical-radio frequency resonance [25, 26].
Considering formulas (3.14)–(3.16) from [26] and the presence of RF field, we obtain the measure of the change of the line contour K (ω) of VR transition η ≈ (d0 E0 / ħ γ)2 ~ 1 at Δωst ≤ γ. That means, the change of the frequency Ω within the limits of the impact half-width of the optical transition γ ≤ 109 s–1 (the gas pressure ~50–200 Тоrr) can both broaden and narrow the line contour K (ω) in comparison with the case when the RF field E0 = 0.
The experiment was carried out with ICLS (the resonator length was ℓ = 9,6, the intermode interval was 15 MHz) with a dynamic Stark cell in a semi-confocal resonator of a ruby laser (the interval between the transverse modes was several units of MHz). The amplitude of electric field at the cell capacitor plates in ICLS varied within the limits 50–300 V/cm. The frequency Ω changed in the range 1–20 MHz characteristic of the repetition rate of the free energy peaks of the laser [16] and the intermode interval of the semi-confocal resonator of the laser [24]. The result of the experiment and the diagrams of the ICLS are shown in Fig. 5.
In the field of 300 V/cm, the maximum increase of γf and the decrease of I(0) are reached at the frequency of Ωy = 5 MHz, and the maximum decrease of γf and increase of I(0) are reached at the frequency of Ωc = 15 MHz. the change of the sign of deformation of the "laydown" contour occurs at the frequency of ΩH = 8,1 MHz. the results of measuring I(0) and γf is 10–15% at the errors in the values of the measured values 4%. The dependence of the "neutral" frequency on the field amplitude is quadratic, that proves the possibility of the control of narrowing the contour of the absorption/reradiation line in the anomalous range by means of the structure of the external e/m field.
2.3. Launch of the self-organization mechanism of nanoparticles in molecules Н2O
The analysis of experimental results and the result of research in 2000–2002 led to an idea of two-dimensional resonance in energy. The two-dimensional resonance is self-organized between the difference 2ω–q = (ω1q – ω2q), the sum 2ω+q = (ω1q + ω2q) of the BR pumping frequencies and the low-frequency k’ → k (starting) ED, high-frequency magnetic multipole (work) k →← n VR transitions. The VR transitions are combined by a lower state k into a V diagram, Fig. 6.
The two-dimensional resonance launches the mechanism of two-dimensional (in space and time) feedback between the energies of the quadratic Stark δWSt⊥∥q = 0 and δW˘Z⊥∥q = 0 Zeeman effects at the extreme conditions for the "CF+MG" system. Here q = 0, 1, 2, 3,...q* = 2ω+q=0 / 2ω–q=0 = 103–106 is the integer number of the step T+q / 4 of the effect of the collective of fields EΣ⊥∥q and HΣ∥⊥q on each molecule.
The collective of fields [13, 14] consists of the vector sum of the electric DC⊥∥q + EB⊥q + DR⊥q + EΣ⊥∥q and the vector sum of magnetic BC∥⊥q + HB∥q + BR∥q + HΣ∥⊥q components of the elastic collision field (C) of molecules with the broadening molecules, pumping BR with p-polarization (B) and the Rayleigh scattering (R). The molecular gas is the working molecules Н2O (mD) and the broadening molecules N2 (mb).
In this case the molecules Н2O in the coherence volume of BR
ΔVq=0 → ΔVq* ≈ Δz∥q*πr2nf⊥q*, (1)
existing in the state k’ participate in the open self-organization of the "CF + MG" system into an optically active ensemble of diamagnetic electron-ion nanoparticles at the MM electron transition prepared in the range of the magnetic multipole k →← n VR transition. Here Δz∥q* and πr2nf⊥q* are the time coherence length and the pumping BR radius, respectively.
The two-dimensional feedback mechanism is realized between the energies of the quadratic Stark δWSt⊥∥q = 0 and δW˘Z⊥∥q = 0 Zeeman effects at the critical conditions for the "CF+MG" system [13, 14].
2ω–q; 2ω+q; I1q / I2q ≠ 1; mb >> Nph >> mD; T°K (2)
The initial Stark δWSt⊥∥q = 0 and Zeeman δW˘Z⊥∥q = 0 energies at the step T+q / 4 provide the increase of fluctuations of the diamagnetic energy up to the threshold value δW˘Z⊥∥q* at the given asymmetry of intensities I1q=0 / I2q=0 ≠ 1; Nph – in the concentration of photons in the volume (1).
Elastic collision of N2 and Н2O induces in Н2O the electric (3)
de⊥∥q = α⊥∥q DC⊥∥q + 1/3 A⊥∥q ∇ DC⊥∥q + G⊥∥q BC⊥∥q ... (3)
and magnetic (4)
dm⊥∥q = –χd∥⊥q ΒC∥⊥q – ~G∥⊥q DC⊥∥q ... (4)
dipole moments [27] with polarizability α⊥∥q, diamagnetic susceptibility –χd∥⊥q, quadrupole polarizability 1/3 A⊥∥γq ∇ D∥γq and tensors G⊥∥q, ~G∥⊥q. The tensors G⊥∥q, ~G∥⊥q are functionally related with the gyration tensor gq of the molecule Н2O.
Iin the range of the ruby laser radiation, we use the V-diagram in the molecule Н2O consisting of two VR transitions
4–3q (000) → 4Е–3k (000) ←→ 5Е–4q (000) (5)
with the common lowest state 4–3q (000).
The state 4–3q (000) of the molecule Н2O is the result of displacement by 2∆JK ≈ 345.6 due to the centrifugal extension [28] and by 2∆JKq due to the elastic collision of Н2O with N2. The state 5Е–4q (000) is the result of displacement due to the collision. Here (000) ⇔ (103) is the vibrational transition of the molecule Н2O and J=4, 5 are the quantum numbers of the angular moment Н2O.
The authors thanks S. N. Bagaev for discussion of the result of the work at the Academic Council of the Institute of Laser Physics SB RAS and S. M. Kobtsev for a discussion of the results of the work, V. G. Bagrov and A. A. Rukhadze for consultations and useful discussions, V. N. Cherepanov and R. R. Valiev for the analytics of the "field collective + molecular gas" system.
The work was supported by the Skolkovo Foundation No. KTIT‑11 on 18.09.2012 and TRINC of the Tomsk Region in 2014.
to be continued
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