Nanosecond Laser Photolysis Spectrometer 

What is the Flash Photolysis technique?

In the nanosecond laser photolysis spectrometer, the output from a pulsed laser is directed onto a sample cuvette at right angles to or colinear with an analysing beam. In order to measure small absorbance changes on a nanosecond time scale, a high intensity, pulsed analysing light source is used to obtain good photometric signal to noise ratios and to reduce the effects of fluorescence and scattered laser light. A carefully designed optical system with aperture stops is used to maximise collection of analysing light passing through the irradiation volume whilst minimising scattered and stray light.
    The use of laser flash photolysis provides a method by which short-lived chemical species, charge-transfer reactions, energy transfer phenomena etc. may be studied with comparative ease. The technique provides one of the most effective methods for producing transient species such as radicals, excited states or ions, in chemical and biological systems, with concentrations high enough to permit characterisation of spectral properties and reactivities by direct observation. The use of a laser for sample excitation gives the technique the specificity of single wavelength excitation and nanosecond time resolution.

Description of the Laser Photolysis Spectrometer

1. Our home designed Laser Flash Photolysis Spectrometer consist of:

Lambda - Physiks Excimer Laser (EMG160ESC), Continuum Nd-YAG Laser (Surelight SLII-10) and Optical Parametric Amplifier, Continuum Nd-YAG Laser (NY81-20) and TiSp Laser (TS-60);

2. Tektronix Oscilloscope (TDS 620) is used as a Signal Digitizer;

3. 100W short ark Xe lamp with modified Bausch & Lomb housing and optics is used to illuminate sample cell through the evacuated McPherson monochromator. Lamp modulation is carried out by ILC illuminator power supply. 

4. Klinger programmable step motor controller is used to control McPherson monochromator.

5. Flow flash cell configuration is similar to the DNA synthesizer. Speed of sample flow as well as flashing and waste management are controlled by central computer.

9. Two Stanford Research generators (model DG 535) are used to synchronize devices.

10. Uniblitz (model D122) shutter driver units are used to control light beams between experiments.

11. PC computer controls the entire experimental setup via GPIB bus. 

Our software allows complete control of data acquisition, spectrometer functions as well as providing comprehensive data analysis.