Schematic layout of the fiber-based single-shot transient absorption apparatus. The inset is an image of the fiber bundle collected by the signal CCD camera after a single laser probe pulse, colored by the light intensity recorded by each CCD pixel (details in text).
Transient absorption bleach data collected at 800 nm for IR140 laser dye in acetone, collected with a single laser excitation pulse (red, lower trace). Also shown is a single base line shot collected without excitation (blue, upper trace).
Transient absorption data of solvated electrons at 760 nm in an argon-purged aqueous solution containing NaOH and 20% methanol. The trace with more apparent noise (red) is an average of 25 shots. The smoother trace (blue) is the same data after correction factors for spatial overlap of the electron beam with the fiber bundle image have been applied.
Representation of the fiber bundle image from the signal CCD camera after a single electron pulse from a different data set (with lower dose, at 800 nm) than used in Fig. 3 to accentuate the spatial overlap of the electron beam with the probe. For emphasis, the fiber spots are color coded to indicate the magnitude of the absorbance due to solvated electrons and thus the distribution of dose from the electron beam. The light colored spots (yellow) indicate fibers with delays before the electron pulse, and have an absorbance .
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