Nanosecond laser flash photolysis (LFP) is an indispensable technique for photoinduced kinetic studies either by transient absorption or time-resolved emission measurements. Despite the commercialization of the instruments that can be used for conducting this type of measurements, many researcher still prefer to assemble their own LFP apparatuses in order to adjust them to the nature of their work and allow optimization and expandability. In this article we described in detail the nanosecond LFP apparatus that has been assembled and used in our laboratory. Significant limitations on this technique are imposed by its sensitivity and the time range that it can cover. These issues have been addressed by a design of a detector assembly that takes advantage of a fast head-on photo-multiplier tube, which is powered through an active bleeder circuit designed after detector circuitry used in high-energy physics experiments. In addition, a high-precision compensating circuit is employed to remove the DC component of the signal. High sensitivity and a working time range from tens of nanoseconds to tens of seconds (or longer) were achieved without compromising the speed of the detection required for nanosecond transient absorption. The described detector and the whole LFP apparatus have considerably simpler control interface in comparison to other instruments of this type. The work of the apparatus is illustrated with examples of transient absorption and time-resolved emission data for solutions of ethyl eosin and terbium (III) dipicolinate complex, respectively.
Valentine I. Vullev and Guilford Jones, II, 2005. Nanosecond Laser Flash Photolysis: Dealing with Dynamic-range and Response-time Limitations of the Detection System. Journal of Applied Sciences, 5: 517-526.