Collisional effects on angular momentum orientation in acetylene X̃ 1Σg+ (ν2″=1,j″). I. Preparation, detection and conservation in single collisions

Abstract

Articles you may be interested inErratum: "Direct determination of state-to-state rotational energy transfer rate constants via a Raman-Raman double resonance technique: ortho-acetylene in v2 = 1 at 155 K" [J. Chem. Phys.132, 154303 (2010)] J. Chem. Phys. 134, 139902 (2011); 10.1063/1.3575199Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels ( X Σ + 2 , v = 2 , N = 0 , 1, 6, 10, 15, and 20) and C 2 H 2 Fate of isolated CH (B 2 Σ − ,v=0,J) states in inelastic collisions with CO

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

“…[39][40][41] The alignment retention they observed was very similar to that reported here, averaging 40% for a range of ∆j = ±2 transitions studied. 39 The simplest models to fit these polarization ratios are ones in which limited ranges of either ∆m j or classical tilt angle, ' jj θ , are allowed.…”

“…We also observe a significant [39][40][41] The orientation and alignment elastic depolarization rates were both measured, and found to be essentially equal, and to decline with increasing j. The similar orientation and alignment rate constants are inconsistent with any simple model in which the magnitude of ∆m j in a single collision is restricted, as these will lead to destruction of alignment faster than orientation.…”

“…[36][37][38] There are fewer more recent experimental studies of other species. Notable exceptions are the work of Rudert et al, who studied elastic depolarization and polarization transfer of both orientation and alignment in C 2 H 2 self-collisions, [39][40][41] and the measurement of alignment transfer in self-collisions of N 2 by Sitz and Farrow. 42,43 Further discussion of these experiments is deferred until later in this paper, but we note that these systems differ in being closed shell and therefore proceeding on single…”

Collisional effects on angular momentum orientation in acetylene X̃ 1Σg+ (ν2″=1,j″). II. Disorientation by rotationally elastic and multiple inelastic collisions

“…1,29 Varying the delay between excitation and detection allows time for the initially oriented molecules to collide with background gas. Such collisions can be rotationally elastic resulting at most in a change of the velocity and/or of the direction of the angular momentum vector and thus in a change of the orientation.…”

“…1 Frequency doubled radiation from a Nd:YAG laser (ϭ532 nm) and a dye laser (Ϸ595 nm) pumped by the Nd:YAG laser excites single rotational states in the C 2 H 2 2 1 carbon-carbon stretch vibration via stimulated Raman pumping. Using oppositely circularly polarized laser beams and transitions in the S-branch high m j levels are preferentially populated, thus strongly orienting the vibrationally excited molecules.…”