Formation and decay of molecular exciplexes in the vapor phase: excitation energy, isotope, and temperature dependence of rate processes in the tetracyanobenzene/p-xylene system

Journal Article · Thu Oct 14 04:00:00 EDT 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100218a007· OSTI ID:6537185

Okajima, S; Lim, E C

The formation and decay of the tetracyanobenzene (TCNB)/p-xylene gas-phase exciplex have been investigated by transient and steady-state fluorescence. The results suggest that the major radiationless transition of the gas-phase TCNB/p-xylene exciplex is S/sub 1/ ..-->.. S/sub 0/ internal conversion, whose rate is controlled by the low-frequency interchromophore vibration as well as high-frequency intrachromophore vibrations. The important intrachromophore accepting modes are argued on valence and experimental grounds, to be methyl C-H stretching vibrations in p-xylene, C-N triple bond stretching vibrations in TCNB, and skeletal stretching vibrations in p-xylene and TCNB. The minor role of the ring hydrogen stretching vibrations in S/sub 1/ ..-->.. S/sub 0/ internal conversion of the exciplex is ascribed to the presence of these good accepting modes. Finally, the radiative decay rate of the exciplex fluorescence has been found to increase with deuteration of methyl hydrogens in p-xylene. The result is consistent with the proposition that the ionization potential of p-xylene-d/sub 3/ is greater than that of p-xylene-d/sub 0/ due to smaller hyperconjugative interaction of CD relative to CH. 17 figures, 2 tables.

• Research Organization: Wayne State Univ., Detroit, MI
• OSTI ID: 6537185
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:21; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
400500 -- Photochemistry
AROMATICS
CHEMICAL REACTION YIELD
CLATHRATES
DATA
DE-EXCITATION
DEUTERIUM
DEUTERIUM COMPOUNDS
DYE LASERS
ELECTROMAGNETIC RADIATION
EMISSION SPECTROSCOPY
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
FLUIDS
FLUORESCENCE SPECTROSCOPY
GASES
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
IONIZATION
IONIZATION POTENTIAL
ISOTOPE EFFECTS
ISOTOPES
LASER RADIATION
LASERS
LIGHT NUCLEI
LIQUID LASERS
MEDIUM PRESSURE
NITRILES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOIONIZATION
PRESSURE DEPENDENCE
RADIATIONLESS DECAY
RADIATIONS
SPECTROSCOPY
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
XYLENE-PARA
XYLENES
YIELDS