Laser-induced fragmentation fluorescence detection of the vinyl radical and acetylene

When excited at lambda = 230 nm, the vinyl radical and acetylene may be det ected via fluorescence from C-2(d(3)Pi (g) -->a(3)Pi (u)) using laser-induc ed fragmentation fluorescence (LIFF). Vinyl photodissociation creates C-2(d (3)Pi (g)) more efficiently than acetylene photodissociation by a factor of 1300-200 depending on the internal excitation of the vinyl radical. The ke y difference in LIFF efficiency between the two molecules depends on the me chanism for loss of the first H atom. This LIFF process may provide a metho d for probing the elusive vinyl radical in methane flames. (C) 2001 Elsevie r Science B.V. All rights reserved.