SHORT PULSEWIDTH REPETITION RATE NANOSECOND TRANSIENT ABSORPTION SPECTROMETER

摘要

A high-sensitivity nanosecond to millisecond transient absorption spectrometer for measurements of miniscule signals under low excitation intensities includes an excitation source generating a frequency greater than 100 Hz, pulsewidth less than 5 ns excitation pulse for exciting a light absorbing sample, a probe light source for generating a photon flux probe light beam producing an average irradiance greater than 1 μW m⁻² nm⁻¹ for measuring the transient absorption spectrum of the sample before and after excitation by the excitation source, a DC-coupled detector capable of measuring light for enabling synchronous measurement of both the transmission of the probe light beam and the change in transmission of the probe light beam between a signal with the excitation pulse present and a signal in the absence of the excitation pulse, and a digital oscilloscope with a trigger rearm time capable of collecting every trigger event at high frequencies including 1 MHz, for enabling sequential noise subtraction protocols.