Transient resonance Raman spectra of benzophenone and its four isotopic analogues in the lowest excited triplet state

Journal Article · Thu Nov 05 04:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100307a013· OSTI ID:5760650

Tahara, T; Hamaguchi, H; Tasumi, M

Transient resonance Raman spectra of T/sub 1/ benzophenone (T/sub 1/BP) and its four isotopic analogues in carbon tetrachloride solutions were measured. Vibrational assignments of eight T/sub 1/ bands have been made on the basis of the observed isotopic frequency shifts. The assignments clarified the following three points concerning the structure of T/sub 1/ BP in solution. (1) The CO bond order in T/sub 1/ BP is much lower than that in the ground-state benzophenone (S/sub 0/ BP). The CO stretching frequency in T/sub 1/ is found to be 1222 cm/sup -1/, whereas the corresponding value in S/sub 0/ is 1665 cm/sup -1/. The former frequency indicates a single-bond-like character of the CO bonding in the T/sub 1/ state. (2) Vibrational frequencies of several ring modes show marked downshifts in going from S/sub 0/ to T/sub 1/. This suggests the delocalization of the ..pi..* electron into the ring part. (3) The assignment (1302 cm/sup -1/) of the symmetric C-phenyl stretch mode in the T/sub 1/ withdraws S/sub 0/ absorption spectrum is questioned. According to the present assignment, the frequency of this mode (approx. 1100 cm/sup -1/) is slightly lower than that in the ground state (1150 cm/sup -1/). The simple quantum chemical picture of T/sub 1/ BP, which predicted the increase of the C-phenyl bond order with the ..pi..* withdraws n excitation, should therefore be reconsidered.

• Research Organization: Univ. of Tokyo, Japan
• OSTI ID: 5760650
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:23; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
400500 -- Photochemistry
BENZOPHENONE
CARBON 13
CARBON ISOTOPES
DATA
DEUTERIUM
DEUTERIUM COMPOUNDS
ENERGY LEVELS
EVEN-ODD NUCLEI
EXCITED STATES
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INELASTIC SCATTERING
INFORMATION
ISOTOPES
ISOTOPIC EXCHANGE
KETONES
LASER SPECTROSCOPY
LIGHT NUCLEI
MULTIPLETS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RAMAN SPECTRA
RAMAN SPECTROSCOPY
RESONANCE SCATTERING
SCATTERING
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
TRIPLETS