Transient Laser Frequency Modulation Spectroscopy

Abstract

Explicitly time-dependent implementations of optical frequency modulation spectroscopy have been recently applied to a wide range of problems in chemical physics. We provide a brief description of the methodology, with an emphasis on its intrinsic advantages for interrogating transient species. Several examples highlight the application of the technique to high-resolution absorption spectra of free radicals, rate measurements for gas-phase reactions, and Doppler spectroscopy of the gas-phase products of photoinitiated reactions.

Frequency modulated circular dichroism spectroscopy: application to ICN photolysis

“…where I ↑↑ and I ↑↓ are the areas of LIF Doppler profiles, or the areas of FM Doppler profiles that have been transformed to 'normal' absorption profiles [49,50], in the corotating and counter-rotating geometries respectively. The parameter V(J), approaches a value of 2 for the high rotational quantum states probed in this work.…”

Elastic depolarization and polarization transfer in CN(A2Π,v= 4)+Ar collisions

“…9 Our experiments measure FM Doppler lineshapes, which may be transformed to conventional Doppler lineshapes by either a stepwise recursive, or numerical 60 This may then be integrated to yield the total line intensity, as described in eqns 1 and 2 above. Figure 1 shows the result of this procedure for the A 2 Π (v = 4, j = 2.5, F 1 , e) state, prepared by pumping the R 1 (1.5) transition of the A-X(4,0) band and probed on the same transition in the A-X(4,2)…”

“…60 In this paper, we adapt this technique, allowing the photolytically generated anisotropic velocity and angular momentum distributions to thermalize, before preparing an aligned sample in a selected A 2 Π(v = 4) rotational state. The evolution of the prepared population and alignment in collisions with Ar is then observed using FMS.…”

Modulation Laser Spectroscopy Method for Ir-Radiation Loses Measurements in Gases

“…Несмотря на значительный прогресс в раз-витии техники оптической частотно-модули-рованной спектроскопии, теоретические мо-дели детально разработаны и изучены только для двухуровневых систем, которые позволя-ют проводить анализ аналитически [1]. К та-ким двухуровневым системам относяться и исследуемые в работе атмосферные смеси на основе метана.…”