Development of a broadband picosecond infrared spectrometer and its incorporation into an existing ultrafast time-resolved resonance Raman, UV/visible, and fluorescence spectroscopic apparatus

• Published in: Applied spectroscopy Vol. 57; no. 4; p. 367
• Main Authors: Towrie, Michael, Grills, David C, Dyer, Joanne, Weinstein, Julia A, Matousek, Pavel, Barton, Robin, Bailey, Philip D, Subramaniam, Naresh, Kwok, Wai M, Ma, Chensheng, Phillips, David, Parker, Anthony W, George, Michael W
• Format: Journal Article
• Language: English
• Published: United States 01.04.2003
• Subjects: DNA - chemistry; Equipment Design; Equipment Failure Analysis; Molecular Probes; Photochemistry - instrumentation; Photochemistry - methods; Quality Control; Signal Processing, Computer-Assisted; Spectrometry, Fluorescence - instrumentation; Spectrometry, Fluorescence - methods; Spectrophotometry, Infrared - instrumentation; Spectrophotometry, Infrared - methods; Spectrophotometry, Ultraviolet - instrumentation; Spectrophotometry, Ultraviolet - methods; Spectrum Analysis, Raman - instrumentation; Spectrum Analysis, Raman - methods; Systems Integration
• ISSN: 0003-7028
• DOI: 10.1366/00037020360625899

We have constructed a broadband ultrafast time-resolved infrared (TRIR) spectrometer and incorporated it into our existing time-resolved spectroscopy apparatus, thus creating a single instrument capable of performing the complementary techniques of femto-/picosecond time-resolved resonance Raman (TR3), fluorescence, and UV/visible/infrared transient absorption spectroscopy. The TRIR spectrometer employs broadband (150 fs, approximately 150 cm(-1) FWHM) mid-infrared probe and reference pulses (generated by difference frequency mixing of near-infrared pulses in type I AgGaS2), which are dispersed over two 64-element linear infrared array detectors (HgCdTe). These are coupled via custom-built data acquisition electronics to a personal computer for data processing. This data acquisition system performs signal handling on a shot-by-shot basis at the 1 kHz repetition rate of the pulsed laser system. The combination of real-time signal processing and the ability to normalize each probe and reference pulse has enabled us to achieve a high sensitivity on the order of deltaOD approximately 10(-4) - 10(-5) with 1 min of acquisition time. We present preliminary picosecond TRIR studies using this spectrometer and also demonstrate how a combination of TRIR and TR3 spectroscopy can provide key information for the full elucidation of a photochemical process.