Oriented molecule beams: Focusing and orientation of t-butyl iodide with analysis by polarized laser photofragmentation

Journal Article · Mon Aug 15 04:00:00 EDT 1988 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.455106· OSTI ID:6934561

Xu, Q; Jung, K; Bernstein, R B

The tert-butyl iodide molecule is readily focused with the electrostatic hexapole, via its first-order Stark effect as a pseudo-symmetric top. The pulsed, seeded supersonic focused beam, characterized by = V/sub th// V/sub 0/ (where theta is the angle between the molecular dipole axis ..mu.. and the electric field E; +- V/sub 0/ the hexapole ''rod voltage,'' and V/sub th/ the so-called threshold voltage), passes into a small homogeneous electric field in which it is oriented. The degree of laboratory orientation achieved is measured using the method of linearly polarized laser-induced photofragmentation (S. R. Gandhi, T. J. Curtiss, and R. B. Bernstein, Phys. Rev. Lett. 59, 2951 (1987)), operating (at three laser wavelengths) on the I(/sup 2/P/sub 3//sub ///sub 2/) and I(/sup 2/P/sub 1//sub ///sub 2/) as well as the t-C/sub 4/H/sub 9/ radical photofragments. The results show that the oriented beam molecules of t-butyl iodide (at a rotational temperature near 15 K) have a higher degree of orientation than the prototype CH/sub 3/I molecules (JKM state-selected and focused similarly), explainable by the greater importance of the so-called hyperfine disorientation effect for the prolate symmetric top (CH/sub 3/I) than for the t-C/sub 4/H/sub 9/I. For the latter, orientations with photofragment up--down asymmetry ratios as large as a factor of 10 can be achieved, suggesting that t-C/sub 4/H/sub 9/I is an excellent candidate reagent for reactive asymmetry studies.

• Research Organization: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569
• OSTI ID: 6934561
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 89:4; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640301* -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
CHEMICAL REACTIONS
DECOMPOSITION
FOCUSING
HALOGENATED ALIPHATIC HYDROCARBONS
IODINATED ALIPHATIC HYDROCARBONS
METHYL IODIDE
MOLECULAR BEAMS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORIENTATION
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
STARK EFFECT