Eur. Phys. J. D 40, 357-362 (2006)
https://doi.org/10.1140/epjd/e2006-00183-2

Photodissociation dynamics of CF₃I investigated by two-color femtosecond laser pulses

¹ Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, P.R. China
² Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan, 430071, P.R. China
³ Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P.R. China
⁴ Quantum Optics and Laser Science Group, The Blackett Laboratory, Department of Physics, Imperial College, London, SW7 2BW, UK

Corresponding author: ^a liuhongping@wipm.ac.cn

Received: 22 February 2006
Revised: 31 May 2006
Published online: 5 August 2006

Abstract

We report an experimental study of the multiphoton dissociation dynamics of CF₃I performed on a home-built femtosecond laser pump-probe system, with time-of-flight mass spectrometer. The first repulsive A band and the 5pπ³7sσ υ₂=1 Rydberg state of CF₃I were accessed by one- and two-photon transitions at 267 nm, respectively, with the latter two-photon absorption followed by a further two-photon probe transition at 401 nm to the state of the parent ion. The observed signals from the CF₃⁺ and I⁺ fragments show similar multi-component exponential decay patterns but the former is 4 times stronger than the latter. However, the parent CF₃I⁺ signal was observed to evolve in a very different manner, decreasing sharply when probed in the first 289 fs following excitation and subsequently rising again after 860 fs to a constant level below that measured at negative pump-probe delay times when the pump and probe pulses exchange roles. This dip observed in the parent ion profile, is very different from that previously reported at shorter pump wavelengths of 264 nm or 265 nm, and is interpreted as the competition between two different ionization channels. One from the vibrationally excited υ₂=1 of the irradiated Rydberg state and the other from the dissociative vibrational origin of the same electronic state which is populated by internal vibrational relaxation.