Picosecond observations of quantum-beat phenomena in 2,5-diphenylfuran and argon complexes

✍ Scribed by Andrew J. Kaziska; Michael R. Topp

• Book ID: 103029886
• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 740 KB
• Volume: 180
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(91)85143-k

✦ Synopsis

Fluorescence time profiles have been measured for vibronically excited PPF and its I : I van der Waals complexes with Ar and CH4. Fluorescence quantum beats (685 MHz) are exhibited in PPF at the low energy of 256 cm-'. Ov&tones and some combination levels involving the 256 cm-' mode also show quantum beats, ranging in frequency from 160 MHz to 3.7 GHz, whereas excitation into other levels up to 877 cm-' shows little vibrational coupling. Experiments with PPF/Ar, and PPF/(CH,), show that this low-energy level mixing in the bare molecule provides a channel for extensive coupling (~tv~ = 300 ps (Ar), I I5 ps ( CH4) from 2X1). On the other hand, excitation of either complex at 867 cm-' reveals weaker coupling, despite the large relative increase in energy; significantly, argon-atom predissociation at this energy is preceded by beat-modulated resonance fluorescence,