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

Journal Article · Thu Nov 05 00:00:00 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), Vol. 91:23
• Country of Publication: United States
• Language: English

Related Subjects

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