Multiphoton-induced picosecond photophysics of chromium(III)-polypyridyl complexes

Journal Article · Thu Mar 26 04:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100291a013· OSTI ID:6800062

Serpone, N; Hoffman, M Z

Transient luminescence studies on a series of Cr(NN)/sub 3//sup 3 +/ complexes (NN = bpy, 4,4'-Me/sub 2/bpy, 4,4'-Ph/sub 2/bpy, phen, 5-Clphen, 5-Brphen, 5-Mephen, 5-Phphen, 4,7-Me/sub 2/phen, 5,6-Me/sub 2/phen, 4,7-Ph/sub 2/phen, and 3,4,7,8-Me/sub 4/phen) have been carried out in aqueous media using picosecond laser excitation at 355 nm with a passively mode-locked Nd:YAG laser (approx.30-ps-fwhm pulses; 2-3 mJ/pulse). Both transient emission and transient absorption (excite-and-prove technique) were examined in detail for Cr(5,6-Me/sub 2/phen)/sub 3//sup 3 +/; excitation wavelengths were 355 and 266 nm. The complexes show a fast emission component at 500-650 nm that decays with tau approx. 50 ps and, except for NN = 5-Phphen and 4,4'-Ph/sub 2/bpy, a slow emission rise (biphasic; tau approx. 0.5 and approx. 10 ns) at lambda greater than or equal to 665 nm in the 0-7-ns window of the streak camera. Transient absorption (355-nm excitation) reveals a pulse-limited formation of a fast decaying transient (tau approx. 50 ps) at 462 nm and a slower decaying transient (tau = 0.5 ns) at 541 nm. In the 1-10-ns range, a slow rise in absorption (outside of experimental error, +/-2sigma) is also observed for NN = 5,6-Me/sub 2/phen. Transient emission studies (266-nm excitation) show, in addition to the fast emission component and the slow emission rise, a prompt emission centered around 460 nm that shows biphasic decay: tau approx. 11 0.6 and 11 +/- 2 ns. In absorption (266-nm excitation), formation of e/sub aq//sup -/ occurs (lambda/sub max/ = 650 nm; Theta/sub e-/ approx. 0.14 at 5 ns).

• Research Organization: Concordia Univ., Montreal Quebec
• OSTI ID: 6800062
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:7; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AZINES
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
EMISSION SPECTROSCOPY
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
LASERS
LIFETIME
LUMINESCENCE
MULTI-PHOTON PROCESSES
NEODYMIUM LASERS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PYRIDINES
SOLID STATE LASERS
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES