Efficient multiphoton dissociation of CF/sub 3/I/sup +/ in the metastable X /sup 2/E/sub 1/2/ excited state using cw infrared laser radiation

Journal Article · Fri May 01 00:00:00 EDT 1981 · J. Chem. Phys.; (United States)

OSTI ID:6535883

Thorne, L R; Beauchamp, J L

Evidence for the multiphoton dissociation of an electronic metastable state of CF/sub 3/I/sup +/ with CO/sub 2/ laser radiation is presented. Only those ions possessing sufficient internal excitation before irradiation can be dissociated. Photodissociation results primarily from resonant absorption by the n/sub 1/ vibrational mode of CF/sub 3/I/sup +/ in the higher of the two, spin--orbit levels of the ground electronic state X /sup 2/E/sub 1/2/. Only the lowest energy decomposition channel is observed; this yields CF/sup +//sub 3/ and I. Spin--orbit and vibrational relaxation compete with photodissociation. At CF/sub 3/I pressures below 2 x 10/sup -7/ Torr, the collisional relaxation rate is proportional to CF/sub 3/I pressure k/sub c/ = (3.1 +- 0.4) x 10/sup -9/ cm/sup 3/ molecule/sup -3/ sec/sup -1/ with a zero pressure rate of 11.3 +- 1.3 sec/sup -1/. The latter rate sets an upper limit on the spin--orbit relaxation rate. The photodissociation probability varies with laser frequency, exhibiting a broad, structureless peak near 960 cm/sup -1/. The initial photodissociation rate is proportional to laser irradiance k/sub D/ = 0.80 +- 0.08 sec/sup -1//W cm/sup -2/. The photoproducts and laser frequency dependence are the same using either cw or pulsed irradiation. Ions were exposed to irradiances up to 120 W cm/sup -2/ cw and fluences up to 1.6 J cm/sup -2/ pulsed. Ion cyclotron resonance (ICR) techniques were used to store and detect the ions.

• Research Organization: Molecular Physics and Chemistry Section, Jet Propulsion Laboratory, Pasadena, California 91125
• OSTI ID: 6535883
• Journal Information: J. Chem. Phys.; (United States), Vol. 74:9
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
FLUORINATED ALIPHATIC HYDROCARBONS
DISSOCIATION
PHOTOLYSIS
IODINATED ALIPHATIC HYDROCARBONS
INFRARED RADIATION
LASER RADIATION
METASTABLE STATES
MOLECULAR IONS
CHARGED PARTICLES
CHEMICAL REACTIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
HALOGENATED ALIPHATIC HYDROCARBONS
IONS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory