Use of ruthenium dyes for subnanosecond detector fidelity testing in real time transient absorption
- CEA, IBITECS, Laboratoire de Photocatalyse et Biohydrogene, F-91191 Gif-sur-Yvette, France and CNRS, URA 2096, F-91191 Gif-sur-Yvette (France)
Transient absorption spectroscopy is a powerful tool for the study of photoreactions on time scales from femtoseconds to seconds. Typically, reactions slower than {approx}1 ns are recorded by the ''classical'' technique; the reaction is triggered by an excitation flash, and absorption changes accompanying the reaction are recorded in real time using a continuous monitoring light beam and a detection system with sufficiently fast response. The pico- and femtosecond region can be accessed by the more recent ''pump-probe'' technique, which circumvents the difficulties of real time detection on a subnanosecond time scale. This is paid for by accumulation of an excessively large number of shots to sample the reaction kinetics. Hence, it is of interest to extend the classical real time technique as far as possible to the subnanosecond range. In order to identify and minimize detection artifacts common on a subnanosecond scale, like overshoot, ringing, and signal reflections, rigorous testing is required of how the detection system responds to fast changes of the monitoring light intensity. Here, we introduce a novel method to create standard signals for detector fidelity testing on a time scale from a few picoseconds to tens of nanoseconds. The signals result from polarized measurements of absorption changes upon excitation of ruthenium complexes {l_brace}[Ru(bpy){sub 3}]{sup 2+} and a less symmetric derivative{r_brace} by a short laser flash. Two types of signals can be created depending on the polarization of the monitoring light with respect to that of the excitation flash: a fast steplike bleaching at magic angle and a monoexponentially decaying bleaching for parallel polarizations. The lifetime of the decay can be easily varied via temperature and viscosity of the solvent. The method is applied to test the performance of a newly developed real time transient absorption setup with 300 ps time resolution and high sensitivity.
- OSTI ID:
- 22053460
- Journal Information:
- Review of Scientific Instruments, Vol. 80, Issue 4; Other Information: (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ABSORPTION SPECTROSCOPY
BLEACHING
DECAY
DETECTION
DYES
EXCITATION
PHOTON BEAMS
POLARIZATION
REACTION KINETICS
REAL TIME SYSTEMS
RUTHENIUM
SIGNALS
SOLVENTS
TIME RESOLUTION
VISIBLE RADIATION