title: Probing chemical reactions: evidence for exploration of an excited potential energy surface at thermal energies.
abstract: The reaction K + NaBr --> KBr + Na is probed during the reactive collision by a continuous wave laser tuned to frequencies not resonant with excitation in either reagents or products. Transient [K..Br..Na] absorbs a laser photon giving [K..Br..Na](*), which can decompose to Na(*) + KBr. Emission from excited Na(*) at the sodium D lines provides direct evidence of laser absorption during the reaction. Different excitation spectra were observed, depending on which sodium D line was monitored. This difference is explicable if, in the absence of the laser, the reaction flux partially bifurcates to a second potential energy surface during the reaction.
authors.forename: M D
authors.initials: MD
authors.lastname: Barnes
authors.forename: P R
authors.initials: PR
authors.lastname: Brooks
authors.forename: R F
authors.initials: RF
authors.lastname: Curl
authors.forename: B R
authors.initials: BR
authors.lastname: Johnson