Short pass filters

The mode of operation of an ion trap can be described in the following way the ions are generated in the central part of the filter by electron ionisation using a short electron pulse. A radiofrequency voltage is then applied to the annular electrode, which confines the ions in the source where they follow complex trajectories in the presence of a low helium pressure of about 0.01 Pa. The mass spectrum is obtained by increasing the radiofrequency amplitude, which destabilises ions of increasing mass. The increase in voltage causes the ions to increase the amplitude of their... 

One additional technique, which is directly related to PM, is the PA excitation (PAE) spectrum [36J. In this technique the wavelength of the excitation source is continuously changed while the intensity of a particular PA band in the PM spectrum is monitored. This is readily done using a powerful xenon lamp coupled to a monochromator equipped with several long- and short-pass filter combinations. The PAE spectra are usually used for studying the excited electronic states of the polymer samples rather than the photoexcitations themselves (361. They can yield information, for example, on the location of the lowest allowed exciton (l u), the continuum threshold, and other important electronic states above it. This complementary information is useful in relation to PL and its excitation spectrum. 

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