Extraction time-delay

Both Porter s original flash photolysis apparatus and Pimentel s rapid scan spectrometer recorded the whole spectral region in a time which was short compared to the decay of the transient species. Kinetic information was obtained by repeatedly firing the photolytic flash lamp and making each spectroscopic measurement at a different time delay after each flash. The decay rate could then be extracted from this series of delayed spectra. Such a process clearly has limitations, particularly for IR measurements, where the decay must be slow compared to the scan rate of the spectrum. 

One way to reduce the kinetic energy spread is to introduce a time delay between ion formation and acceleration, referred to as delayed pulsed extraction. After a certain time delay ranging from nanoseconds to microseconds a voltage pulse is applied to accelerate the ions out of the source. 

The way to improve LIBS analytical abilities is double pulse LIBS. It is conducted by using two pulses from the same laser source operated at a single wavelength. By utilizing a modified commercial laser, a proper external trigger circuit allows us to extract two laser pulses with adjustable delay from the same flash-lamp emission, and a relative time delay variable from a few to several tenths of microseconds. The experimental results show that such a technique... 

Bahr, U., Stahl-Zeng, J., Gleitsmann, E., and Karas, M. (1997). Delayed extraction time of flight MALDI mass spectrometry of proteins above 25,000 Da.. Mass Spectrom. 32, 1111-1116. 

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