The direct detection of an aryl azide excited state: an ultrafast study of the photochemistry of para- and ortho-biphenyl azide.
Ultrafast laser flash photolysis (266 nm) of para- and ortho-biphenyl azide in acetonitrile produces azide excited states that have broad absorption bands centered at 480 nm. The para-biphenyl azide excited singlet state has a lifetime of 100 fs. The excited-state lifetime of the ortho-azide isomer is 450 +/- 150 fs. Decay of the azide excited states is accompanied by the formation of the corresponding known singlet nitrenes (para, lambdamax = 350 nm, ortho, lambdamax = 400 nm). Singlet para-biphenylnitrene is born with excess energy and undergoes vibrational cooling with a time constant of 11 ps to form the long-lived (tau approximately 9 ns) relaxed singlet nitrene. Singlet ortho-biphenylnitrene decays with a lifetime of 16 ps in acetonitrile at ambient temperature.
Burdzinski
Gotard T
GT
Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University, 85 Umultowska, Poznan 61-614, Poland.
Gustafson
Terry L
TL
Hackett
John C
JC
Hadad
Christopher M
CM
Platz
Matthew S
MS
D001386:Azides / Q000737:chemistry* / Q000528:radiation effects; D001713:Biphenyl Compounds / Q000737:chemistry* / Q000528:radiation effects; D015394:Molecular Structure; D010777:Photochemistry; D014466:Ultraviolet Rays
D001386:Azides; D001713:Biphenyl Compounds; C506735:ortho-biphenyl azide