A state-selected continuous wave laser excitation method for determining CO2’s rotational state distribution in a supersonic molecular beam

Review of Scientific Instruments, vol. 95

Abstract

State-resolved experiments can provide fundamental insight into the mechanisms behind chemical reactions. Here, we describe our methods for characterizing state-resolved experiments probing the outcome of the collision between CO2 molecules and surfaces. We create a molecular beam from a supersonic expansion that passes through an ultra-high vacuum system. The CO2 is vibrationally excited by a continuous wave infrared (IR) laser using rapid adiabatic passage. We attenuate the fractional excitation using a CO2 absorption cell in the IR beam path. We combine Monte Carlo simulations and molecular beam energy measurements to find the initial rotational state distribution of the molecular beam. We find that our pure CO2 beam from a 300 K source has a rotational temperature of ∼26 K.

Authors 3

1. Ludo B. F. Juurlink Aachen Leiden Institute of Chemistry

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University 1 , P.O. Box 9502, 2300RA Leiden, The Netherlands

2. Richard van Lent Aachen Leiden Institute of Chemistry

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University 1 , P.O. Box 9502, 2300RA Leiden, The Netherlands

3. Helen Chadwick

   Swansea University

   Affiliation as printed

   Department of Chemistry, Faculty of Science and Engineering, Swansea University 2 , Swansea SA2 8PP, United Kingdom