Lineshape theory for three-level double resonance in the presence of infrared laser radiation
06 Jun 1986-Chemical Physics Letters (North-Holland)-Vol. 127, Iss: 2, pp 157-162
TL;DR: In this paper, a set of coupled optical Bloch equations has been solved to obtain the absorption lineshape for both copropagating and counter-propagating three-level double resonances in the presence of a strong infrared laser source.
About: This article is published in Chemical Physics Letters.The article was published on 1986-06-06. It has received 4 citations till now. The article focuses on the topics: Far-infrared laser & Resonance.
TL;DR: In this paper, strong double-resonance signals are observed in silane pumped with a TEA-CO 2 laser and probed with a tunable diode laser, and the lineshapes of these signals have been modeled with an extension of three level density matrix theory to the case of a large bandwidth pump laser.
TL;DR: In this article, the interaction of two electromagnetic radiations with a four-level atom with two closely spaced common levels is studied for the cascade system, where the spacing between the close levels is assumed to be small so that the radiation frequency can act simultaneously on the two closely-spaced resonances.
TL;DR: In this paper, the line shape calculation of a weak microwave signal in the presence of a strong radio frequency pump was performed and it was shown that the Bloch-Siegert shift of the pump resonance frequency can produce a shift and asymmetry of the Rabi frequency components of the signal for on-resonance pumping.
TL;DR: In this paper, a three-level system driven by a strong infrared pump pulse of duration t p and a weak cw infrared signal is solved to obtain the time-dependent signal absorption lineshape for 0 t tp and t > t p.
TL;DR: In this article, double resonance signals appear as narrow transmission peaks on the diode laser scans and are recorded using a computer-aided, rapid scan, digital signal averaging technique.
Abstract: Double resonance experiments on NH3 are described in which a CO laser pumps a 6 μm ν4 transition while a tunable diode laser probes a 10 μm ν2 transition having a common lower level. Four different combinations of pump–probe transitions are studied. The CO laser is Lamb‐dip stabilized on the pump transitions, which are tuned into coincidence with it using a precision intracavity Stark cell. The pump and probe beams overlap colinearly in the Stark cell. The double resonance signals appear as narrow transmission peaks on the diode laser scans. The narrowest observed widths are ≂3 MHz (FWHM), a large portion of which is due to unresolved hyperfine structure. An analysis of the various broadening mechanisms indicates that the diode laser contributes less than 1 MHz to the widths. Resonances due to velocity‐preserving but state‐changing collisions are seen. Asymmetries between co‐ and counterpropagating linewidths are shown to arise from a combination of field inhomogeneity and coherent narrowing effects. The data are recorded using a computer‐aided, rapid‐scan, digital signal averaging technique.
TL;DR: In this article, a theory of line shape for a Doppler broadened probe in the presence of a strong infrared pump is presented; the T1, T2 relaxations are introduced phenomenologically in these equations.
Abstract: A theory of line shape for a Doppler broadened probe in the presence of a strong infrared pump is presented. The optical analog of Bloch equations has been developed; the T1, T2 relaxations are introduced phenomenologically in these equations. Doppler broadening of both the pump and signal transitions are taken into account to obtain the absorption coefficient for the signal. This leads to a Doppler broadened Gaussian function weighted by a pump induced Lorentzian function whose position and linewidth are controlled by the detuning and power respectively of the pump radiation. The absorption coefficient is further modulated by a Lorentzian function containing the fourth power of the radiation. The off‐resonance pumping leads to two symmetrically located ‘‘Lamb dips’’ or ‘‘peaks’’ around the Gaussian pedestal for co‐ and counter propagating laser radiations. A calculation of the line shape of the central sub‐Doppler feature for the on‐resonance pumping is in good agreement with the observed variation of li...
TL;DR: In this article, a series of accidental three-level double resonances are observed in the nonlinear Stark spectrum of 15 NH 3 obtained with a CO laser and an intracavity cell.
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