Filters Band-pass filter

The main problem has been a methodological one. The patch clamp analysis of single channels views the world of channels through a very small analytical window [10]. A single channel event (opening) needs to be sufficiently long-lived and sufficiently large to be picked up within the current noise band under optimized conditions, and with the low-pass filter set to say 2 kHz. The open time needs to be close to a millisecond and the current amplitude close to 0.5 pA to permit detection. 

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. 

Liu DS, Knauf PA and Kennedy SD (1996) Detection of cr binding to band-3 by double quantum filtered C1 nuclear magnetic resonance. Biophysics Journal 70 715-722. 

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