Matrix perdeuteration effects on the /sup 3/. pi pi -->. S/sub 0/ phosphorescence of p-chlorobenzaldehyde at 4. 2degreeK. I. Phenomenology

Journal Article · Mon Nov 15 04:00:00 EST 1976 · J. Chem. Phys.; (United States)

OSTI ID:7351454

Khalil, O S; Goodman, L

The effect of matrix perdeuteration and variation of cooling rate on the phosphorescence vibrational structure of p-chlorobenzaldehyde (PCB) are studied in methylcyclohexane (MCH) and p-xylene. PCB shows very different phosphorescence spectra in slowly cooled MCH-h/sub 14/ and MCH-d/sub 14/, generally broad spectra in fast cooled samples, and a mixture of the two phosphorescences (observed in the slow cooled sample) in intermediate cooled MCH-d/sub 14/. In p-xylene, no change in the phosphorescence vibrational structure is observed on matrix perdeuteration. These observations are interpreted by postulating two crystalline modifications for methylcyclohexane, one of them stable in slowly cooled MCH-h/sub 14/, the other stable in slowly cooled MCH-d/sub 14/. The spectra of PCB is different in the two modifications. The anomalous response of the PCB phosphorescence vibrational structure to the crystalline modifications of MCH is indicative of a large degree of distortability in its /sup 3/..pi pi..* state. The distortability is interpreted as originating from vibrational--electronic interactions between the closely spaced /sup 3/..pi pi..*--/sup 3/n..pi..* states. Support for this view is found in the phosphorescence spectra of various deuterated derivatives of PCB in perprotonated and perdeuterated MCH. The apparent distortability of the emitting state varies with the extent of deuteration. (AIP)

• Research Organization: Wright and Rieman Chemistry Laboratories, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903
• OSTI ID: 7351454
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 65:10; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ALDEHYDES
BENZALDEHYDE
DEUTERIUM
ENERGY LEVELS
EXCITED STATES
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
LUMINESCENCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOSPHORESCENCE
STABLE ISOTOPES