Timing the Acetylene-Vinylidene Isomerization Using Ultra Short Laser Pulses

A.S. Alnaser, T. Osipov, S. Voss, C. Mahrajan, P. Ranitovic, B. Ulrich, I. Litvinyuk, B. Shan, Z. Chang, C.L. Cocke
(J.R.Macdonald Laboratory, Physics Department, Kansas State Univ),

A.L. Landers
(Physics Dept.-Auburn Univ.),

E. Wells
(Physics Dept.-Augustana College)

The isomerization of acetylene to vinylidene has been investigated for many years. Very recently, the upper limit for the time of the rearrangement in the dication has been deduced experimentally in the photo-ionization of the carbon K-shell from acetylene [1]. In this work, we used COLTRIMS and measured in coincidence the ion pairs produced in the fragmentation of acetylene after being doubly ionized by intense short laser pulses. Using the fragments' momentum spectra, the acetylene and vinylidene breakup channels are clearly isolated. Additionally, using two ultra-short laser pulses with variable delay in a pump-probe arrangement, important information about the isomerization time can be obtained.

[1] T. Osipov, et. al., Phys. Rev. Lett.90, 233002 (2003).

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to DAMOP, May 2004 in Tucson, AZ.

 

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