Orientation of benzene in supersonic expansions, probed by IR-laser absorption and by molecular beam scattering

• Published in: Physical review letters Vol. 86; no. 22; p. 5035
• Main Authors: Pirani, F, Cappelletti, D, Bartolomei, M, Aquilanti, V, Scotoni, M, Vescovi, M, Ascenzi, D, Bassi, D
• Format: Journal Article
• Language: English
• Published: United States 28.05.2001
• ISSN: 0031-9007
• DOI: 10.1103/physrevlett.86.5035

This work represents the first experimental demonstration that planar molecules tend to travel as a "frisbee" when a gaseous mixture with lighter carriers expands into a vacuum, the orientation being due to collisions. The molecule is benzene, the prototype of aromatic chemistry. The demonstration is via two complementary experiments: interrogating benzene by IR-laser light and controlling its orientation by selective scattering on rare gas targets. The results cast new light on the microscopic mechanisms of collisional alignment and suggest a useful way to produce intense beams of aligned molecules, permitting studies of steric effects in gas-phase processes and in surface catalysis.