Laser Physics Letters

Beating in free polarization decay

Гольдорт Вениамин Гершевич, Ледовских Дмитрий Васильевич, Хворостов Евгений Борисович, Н. Н. Рубцова

Published Dec 10, 2007• 5 citations

Abstract

Free polarization decay formed by Stark switching technique in a presence of 9P(32) CO2 laser low intensity radiation in a low pressure gas 13CH3F is investigated as a function of Stark field strength. Rotation transition R(4,3) of vibrational mode 0 ↔ 1 ν3 was used. The beatings between free polarization signals originating from transitions with different magnetic quantum numbers appeared as periodic peaks with the period inversely proportional to the Stark field strength. The weighted difference between permanent dipole moments of upper and lower vibration states is estimated from these data, in agreement with known values of permanent dipole moments.

DOI: 10.1002/lapl.200710118

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Laser Physics Letters

Beating in free polarization decay

Гольдорт Вениамин Гершевич, Ледовских Дмитрий Васильевич, Хворостов Евгений Борисович, Н. Н. Рубцова

Published Dec 10, 2007• 5 citations

Publisher

Abstract

DOI: 10.1002/lapl.200710118

Related papers

Coherent Transients in a Gas 13CH3F Generated by Step Switch of Electric Field

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Transient signals of optical nutations and free polarization decay arising in a gas 13CH3F (rotational transition R(4,3) of vibration mode 0–1 ν3 ) at the step-wise switch of electric field in the presence of resonant radiation of CO2 laser are investigated. In the limit of low intensity of radiation the peaks of free polarization decay are observed; the frequency of their appearance is proportional to the electric field strength. The number of observable peaks of free polarization decay decreases at laser intensity growth, and free polarization decay signal becomes indistinguishable at a background of optical nutations at high laser intensity. At high laser intensity the signal of transient optical nutations dominates. Results of calculations are in qualitative agreement with experimental dataTransient signals of optical nutations and free polarization decay arising in a gas 13CH3F (rotational transition R(4,3) of vibration mode 0–1 ν3 ) at the step-wise switch of electric field in the presence of resonant radiation of CO2 laser are investigated. In the limit of low intensity of radiation the peaks of free polarization decay are observed; the frequency of their appearance is proportional to the electric field strength. The number of observable peaks of free polarization decay decreases at laser intensity growth, and free polarization decay signal becomes indistinguishable at a background of optical nutations at high laser intensity. At high laser intensity the signal of transient optical nutations dominates. Results of calculations are in qualitative agreement with experimental data

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Physical Review AOct 1, 19798 citations

The authors study the phenomenon of coherent Raman beats in

^{15}\mathrm{N}

{\mathrm{H}}_{3}

using a C

{\mathrm{O}}_{2}

laser and Stark switching. In particular, a three-level system in which the two upper levels always remain split by a few MHz is prepared by switching the transitions into resonance with a short Stark pulse whose bandwidth is large enough to coherently excite both transitions. When one of the coherently excited levels remains in resonance with the laser after the Stark pulse, this system exhibits a qualitatively new effect which has not been seen heretofore. For Stark shifts on the order of the upper-state splitting or smaller, the Raman beat is amplitude modulated at a frequency related to the optical nutation frequency. This is interpreted as being due to an interaction between the two-photon coherent Raman beat process and a single-photon optical nutation process which occurs simultaneously. Numerical calculations as well as a simple analytic model are presented to support this interpretation. By reducing the laser power, one can make the modulation of the Raman beat disappear. From the Raman signal in this regime the permanent electric dipole moment of

^{15}\mathrm{N}

{\mathrm{H}}_{3}

in an excited vibrational state is determined and the Raman beat decay rate measured. By comparing the latter result with a delayed optical nutation measurement we show that phase-changing collisions are negligible for the transition studied.