Fluorescence filters

Alkaloids, e.g. cocaine, ecgonine, benzoylecgonine, ecgonine methyl ester 280 °C, 8 min or 260°C, 10-30 min Pale blue induced fluorescence (Xn > 390 nm, cut off filter), fluorescence amplification by a factor of 2 on dipping in liquid paraffin solution detection limits <10 ng. [13]... 

Xn > 390 nm, cut off filter), fluorescence amplification by a factor of 2 on dipping in liquid paraffin solution detection limits <10 ng. 

Fluorescence with emission filter Fluorescence with six... 

The downside of the compact design and the high numerieal aperture is that the systems are vulnerable to optical reflections. Reflections are particularly likely between the PMT cathode and an interference filter, or between an interference filter and another flat optical surface (see Sect. 7.2.6, page 285). Replacing an interference filter with an absorptive filter solves most reflection problems, but often causes problems by filter fluorescence. 

A problem of absorptive filters in TCSPC applications can be fluorescence of the filter glass. The lifetimes of filter fluorescence can be anywhere between a nanosecond and tens of microseconds. Figure 7.13 shows the fluoreseence decay of a GG 420 and a GG 475 fdter. 

If the lifetime of the filter fluorescence is long, the result is an apparent inerease in the baekground eount rate, which is often mistaken for deteetor baekground or leakage of daylight. Absorptive filters should be cheeked for possible lumines-eenee and, if possible, should be placed far away from any image plane eonju-gated with the deteetor. 

Phagocytosis of microspheres and bacteria is determined using phase-contrast microscopy with a green fluorescent filter. Fluorescent-dyed microspheies and... 

Development of Fourier transform [64 66] and Fladamer transform [67] spectrometers as detectors in Raman spectroscopy, similar to FTIR it has recently been shown that with the proper masking of the Rayleigh scattered radiation and special optical filters, fluorescence-free Raman spectra can be obtained [64]. 

Picosecond measurements were performed at room temperature at 750 nm and 800 nm, giving preferential excitation of BChl c and a respectively. Anisotropy measurements were made with the exciting light polarized parallel or perpendicular to the measuring light. Isotropic measurements were made with the polarization set to 54.7. The excitation Intensity was varied with neutral density filters. Fluorescence spectra and were measured on a Spex Fluorolog spectrometer. The anisotropy was calculated from Iu-Ij /(Ii i+2Ii), where I i and Ii are the intensity of the absorbance or fluorescence signal. 

There are a variety of well-known problems associated with the time correlated single photon counting technique (11), the technique most commonly used for measuring fluorescence decays in synthetic polymer systems. Some are seemingly trivial (some filters fluoresce) until one stumbles across them. Others require rather delicate judgment. Among the latter, two problems are particularly noteworthy First, it... 

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