Spectrophotometer luminescence

Ultraviolet absorption spectra were obtained from a Cary 118C Spectrophotometer. Luminescence measurements were obtained from a Perkin-Elmer Model MPF-3 Fluorescence Spectrophotometer equipped with Corrected Spectra, Phosphorescence and Front Surface Accessories. A Tektronix Model 510N Storage Oscilloscope was used for luminescence lifetime measurements. Fiber irradiation photolyses were carried out in a Rayonet Type RS Model RPR-208 Preparative Photochemical Reactor equipped with a MGR-100 Merry-go-Round assembly. 

Electronic Absorption and Emission Spectroscopy. UV and visible spectra were recorded on Cary 14, Cary 171, or Perkin-Elmer 576 ST spectrophotometers. Luminescence excitation and emission spectra. were recorded on an Hitachi-Perkin-Elmer MPF-2A spectrofluorimeter equipped with a red-sensitive Hamamatsu R-446 photomultiplier tube. Conventional flash photolysis experiments were performed as described previously (41). The samples were degassed by several cycles of freeze-pump-thaw and sealed under vacuum. 

Retzik, M. and Froehlich, P., Extending the capability of luminescence spectroscopy with a rapid-scanning fluorescence spectrophotometer, Am. Lab., March, 68, 1992. 

Comparing this value to the typical sensitivity provided by a spectrophotometer, (OT>)niin = 5 X 10 (see Section 1.4), we see that the luminescence technique is much more sensitive than the absorption technique (about 10 times for this experiment). Although this large sensitivity is an advantage of photoluminescence, care must be taken, as signals from undesired trace luminescent elements (not related to our luminescent center) can overlap with our luminescent signal. 

Phosphors for cathode-ray tubes, television screens, monitor screens, radar screens, and oscilloscopes are tested under electron excitation. Electron energy and density should be similar to the conditions of the tube in which the screen will be used. The phosphors are sedimented or brushed onto light-permeable screens and coated with an evaporated aluminum coating to dissipate charge. The luminescence brightness and color of the emitted light are measured with optical instruments such as photomultipliers or spectrophotometers. 

CFDA (Sigma) is used at 40 )Ug/ml final concentration in serum free medium, 0.1% BSA, pH 6.0, for 30 min at 37°C. At the end of the assay, adherent labeled tumor cells are placed in 0.2% SDS for 30 min at 37°C to release the fluorescent marker. Three volumes of calcium-magnesium-free-PBS are added, and the fluorescence of the cell lysate is measured with a Perkin-Elmer LS-5 luminescence spectrophotometer (excitation maximum 485 nm, emission maximum 538 nm) (Price et al., 1995). 

Energies in the infrared spectrum are conventionally expressed in wave numbers, which are defined as the number of waves per centimeter, i.e., the reciprocal of the wavelength measured in centimeters. The infrared spectrum extends from 12,500 to 50 cm (i.e., a wavelength of 0.8-200 fjLia.) and the far infrared from 40-10 cm (260 p.m-1 mm), but the upper limit of most commercial instruments is about 200 cm (50 ixm). Spectra are most frequently obtained by absorption and reflection techniques, but polarization, emission, and luminescence are also used (C26). Similar components are used in all types of instrument. Reflection measurements of samples with low transmission are made in the near infrared with a conventional spectrophotometer fitted with a reflec-... 

Become familiar with the operation of the fluorescence spectrophotometer in your laboratory. In particular, you should understand how the following instrumental parameters affect the intensity and signal-to-noise ratio (S/N) of a luminescence spectrum ... 

Q8.10 Why should instrumental parameters on the fluorescence spectrophotometer not be changed when measuring luminescence intensities for a given series of solutions ... 

Bioluminescence spectra. BL spectra were recorded using a Cary-Eclipse luminescence spectrophotometer (Varian) from 400-700 nm wavelengths. 

The formed colloidal solutions with nanoparticles were characterized by optical absorption and photoluminescence spectroscopy for monitoring the changes in the plasmon absorption characteristics and luminescence properties, transmission electron microscopy (TEM) and X-ray diffraction (XRD) in order to analyze the final size and structure of nanoparticles. The absorption spectra of the colloids were recorded with a UV-visible spectrophotometer (CARY 500) using a 1-cm-pathlength-quartz cell for the absorption measurements. 

Spectroscopic Measurements. Absorption spectra were obtained using a Perkin-Elmer Model 554 Spectrophotometer and phosphorescence spectra and mean lifetimes were obtained at 77 K using a Perkin-Elmer LS-5 Luminescence Spectrometer coupled to a 3600 data station. Phosphorescence quantum yields were obtained by the relative method using benzophenone (0p = 0.74 in ethanol glass at 77 K) as a standard (11). 

Absorption and luminescence spectra for thin films and devices using copolymers were measured with a Shimadzu UV-365 spectrophotometer and a Hitachi 850 fluorescence spectrophotometer, respectively. Luminance and current-voltage curves were obtained with a TOPCON BM-8 luminance meter, a Keithley 990 digital multimeter and a Takasago GP050-2 DC voltage source which were controlled with a personal computer. 

Luminescence Spectroscopy. Photoluminescence measurements were performed with the aid of a Fluorolog3 spectro-fluorometer Fl3—22 (Horibajobin Yvon) equipped with double Czerny—Turner monochromators, a 450 W xenon lamp and a R928P photomultiplier with a photon counting system. Cooling down to 10 K was achieved by a closed cycle He cryostat (Janis Research). All emission spectra were corrected for the photomultiplier sensitivity and all excitation spectra for the intensity of the excitation source. To avoid any contamination of water on the sample s surfaces, we carried out the measurements in silica ampules with extreme purity which show no luminescence of the ampules itself. Reflection spectra were recorded on a Cary 5000 UV—vis—NIR spectrophotometer (Varian), which were corrected for both the lamp intensity and the photomultiplier sensitivity. 

The first detector to be used for SFA was a photometer, and photometric determinations still form the vast majority of current methods. Other detectors in common use are UV spectrophotometers, used primarily for pharmaceutical compovmds and for bitterness in beer flame photometers, for potassium and sodium determination fluorimeters, used primarily for measuring low levels of determinants in the presence of interferences, such as the determination of histamine in blood, and vitamins in food extracts and ion-selective electrode and pH detectors. In principle, almost any detector with flow-through capability can be used with SFA systems, and determinations based on densitometry, thermometry, and luminescence have been published, among others. 

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