UV multiple-photon dissociation of Cr(CO)/sub 6/ to Cr* and CO: evidence for direct and sequential dissociation processes

Journal Article · Wed Jan 21 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00236a046· OSTI ID:6948445

Tyndall, G W; Jackson, R L

Gas-phase photodissociation of metal carbonyls to metal atoms and CO is well-known. Multiphoton ionization experiments have shown that dissociation of the carbonyls to ground- and excited-state metal atoms is unexpectedly efficient relative to competing ionization processes. Because the mechanisms behind metal atom formation are not entirely clear, they have investigated the KrF* laser (248 nm) multiple-photon dissociation of Cr(CO)/sub 6/ to Cr* and CO in the gas phase. They present evidence that Cr* is formed by two processes: (1) a direct process, where Cr(CO)/sub 6/ is excited into a dissociative continuum, and (2) a sequential process, where a Cr(CO)/sub 4/ intermediate photoproduct absorbs an additional photon to produce Cr*. They monitored formation of Cr* by detecting the emission obtained upon unfocused KrF* laser irradiation of approx. 20 mtorr of Cr(CO)/sub 6/ contained in a flow cell. Laser fluences ranged from 3 to 40 mJ cm/sup -2/. Emission normal to the laser beam was dispersed by a monochromator (resolution 0.5-2 A) and detected by a photomultiplier tube in conjunction with a boxcar integrator. Standard lamps were used to calibrate the optical system.

• Research Organization: IBM Almaden Research Center, San Jose, CA
• OSTI ID: 6948445
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:2; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
CARBONYLS
CHEMICAL REACTIONS
CHEMISTRY
CHROMIUM COMPOUNDS
DATA
DISSOCIATION
ENERGY LEVELS
EXCIMER LASERS
EXCITED STATES
EXPERIMENTAL DATA
FLUIDS
GAS LASERS
GASES
INFORMATION
LASERS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
REACTION INTERMEDIATES
TRANSITION ELEMENT COMPOUNDS