Controlling molecular angular momentum orientation by Raman pumping and optical ac Stark effect

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.…”

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

“…Although the agreement is satisfactory, the fact that all of the measured initial orientations lie above the theoretically determined maximum is significant and can be attributed to the ac Stark effect which has been further verified by examining Raman pumping profiles. 10 One should bear in mind that by using Eq. ͑13͒ one will consistently undermeasure the orientation.…”

“…2 are obtained at the peak of the Raman profile, which is displaced from the position where calculations including the ac Stark effect predict the maximum orientation will be observed. 10 The relatively weak Raman cross-sections make it difficult to measure orientations under conditions where no Stark broadening is present. More detailed discussions of these high field effects can be found in Ref.…”

“…At higher intensities the ac Stark effect lifts the energetic degeneracy of the m j -levels, and with narrow bandwidth excitation radiation the anisotropy of the m j -population can be enhanced. [8][9][10] Within the last few years molecular alignment in supersonic expansions, which may be thought of as the inverse problem, has received a great deal of interest. 11,12 Observation of collisional orientation changes can be used to test ab initio potential energy surfaces in much the same way as the spectroscopy of van der Waals complexes has been used in the past decade 13 or measurements of complete sets of rotational energy transfer cross-sections can do.…”

Autler–Townes splitting and the AC Stark effect in nonpolar molecules: Prospects for all-optical alignment

“…They were able to selectively excite the |m J | = J state by AC Stark shifting all states with |m J | = J away from resonance using a coupling laser tuned to an R-branch transition. Finally, most recently, Rudert et al [9] used the AC Stark shifting of the Raman pump beam to partially resolve the |m J | contributions to the Raman line shape for a transition in acetylene.…”