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
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.
PACS: 33.70.Ca – Oscillator and band strengths, lifetimes, transition moments, and Franck-Condon factors / 33.80.Rv – Multiphoton ionization and excitation to highly excited states / 33.80.Gj – Diffuse spectra; predissociation, photodissociation / 82.53.Eb – Pump probe studies of photodissociation
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006