Date

2015

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Physics

First Adviser

Huennekens, John

Other advisers/committee members

Deleo, Gary; Hickman, A. Peet; Dierolf, Volkmar; Ferguson, Gregory S.

Abstract

We have investigated collisions of NaK molecules in the first excited state [2(A)1Σ+], with Ar and He collision partners using laser-induced fluorescence spectroscopy (LIF) and polarization-labeling (PL) spectroscopy in a two-step excitation scheme. Additionally, we have investigated collisions of NaCs molecules in the first excited state [2(A)¹Σ+] with Ar and He perturbers using the LIF technique. We use a pump-probe, two-step excitation process. The pump laser prepares the molecule in a particular ro-vibrational (v, J) level in the A state. The probe laser frequency is scanned over transitions to the 3¹Π in NaK or to the 5³Π in NaCs. In addition to observing strong direct lines, we also see weak collisional satellite lines that arise from collisions in the intermediate state that take the molecule from the prepared level (v, J) to level (v, J + ΔJ). The ratio of the intensity of the collisional line to the intensity of the direct line in LIF and PL yield information about population and orientation transfer. Our results show a propensity for ΔJ=even collisions of NaK with Ar and an even stronger propensity for collisions with He. Collisions of NaCs with Ar do not show any such ΔJ=even propensity. Preliminary investigations of collisions of NaCs with He seem to indicate a slight ΔJ=even propensity. In addition, we observe that rotationally inelastic collisions of excited NaK molecules with potassium atoms destroy almost all of the orientation, while collisions with argon destroy about one third to two thirds and collisions with helium destroy only about zero to one third of the initial orientation.

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