Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility.
When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm(-1). The response time of the TRIR detection setup is ∼40 ns, with a typical sensitivity of ∼100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.
Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
David C
DC
Grills
Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
Jaime A
JA
Farrington
Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
Bobby H
BH
Layne
Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
Jack M
JM
Preses
Department of Mathematics and Computer Science, Dowling College, 1300 William Floyd Parkway, Shirley, New York 11967, USA.
Herbert J
HJ
Bernstein
Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
James F
JF
Wishart