POPOP

ANSt (free acid) Ethanol 0.38 Anthracene 0.39 POPOP... 

Fluorescein, ethyl ester O.lNNaOH 0.99 Quinine sulfate 0.99 POPOP... 

TNSf (potassium salt) Ethanol 0.48 Anthracene 0.51 POPOP... 

POPOP p-bis[2-(5-phenyloxazoyl)]benzene. t ANS, anilino-8-naphthalene sulfonic acid. t TNS, 2-p-toluidinylnaphthalene-6-sulfonate. 

The 3700A wavelength photons interact and excite the POPOP molecules. The POPOP in... 

The excited POPOP molecules go to the ground state via the emission of photons with... 

The addition of a secondary solute or wavelength shifter can serve to offset much if not all of the action of tagged nitrocompds in reducing counting efficiency. For expl nitrocompds, a shift of the emission spectrum considerably into the visible region where absorption effects are not so pronounced is clearly indicated. The secondary solute POPOP has been found to be most efficient for this purpose (Ref 2). This enhanced effect on the scintillation process is illustrated in Fig 2 for p-Nitrotoluene... 

Radioactivity Analysis. Samples of urine, feces, and tissues were combusted to COo and analyzed for radioactivity (5). By using this method the recovery of radioactivity from samples spiked with C was 95 dt 5%. To determine the radioactivity expired as CO2, 5-ml aliquots of the solution used to trap the CO2 were added to 15 ml of a scintillation counting solution containing 4 grams 2,5-diphenyloxazole (PPO) and 0.1 grams l,4-bis-2(5-phenyloxazolyl)-benzene (POPOP) per liter of 1 1 toluene 2-methoxyethanol. Samples were counted for radioactivity in a Nuclear Chicago Mark II liquid scintillation counter. Counting eflSciency was corrected by the internal standard technique. 

In most cases, the linear absorption is measured with standard spectrometers, and the fluorescence properties are obtained with commercially available spectrofluo-rometers using reference samples with well-known <1>F for calibration of the fluorescence quantum yield. In the ultraviolet and visible range, there are many well-known fluorescence quantum yield standards. Anthracene in ethanol (Cresyl Violet in methanol (commonly used reference samples for wavelengths of 350-650 nm. For wavelengths longer than 650 nm, there is a lack of fluorescence references. Recently, a photochemically stable, D-ji-D polymethine molecule has been proposed as a fluorescence standard near 800 nm [57]. This molecule, PD 2631 (chemical structure shown in Fig. 5) in ethanol, has linear absorption and fluorescence spectra of the reference PD 2631 in ethanol to... 

The choice of a matrix tailored for a particular kind of polymer sample is cmcial for successful characterization of the sample. Therefore, it is useful to discuss the properties of some common matrices [4—6], 3-Amino-4-hydroxybenzoic acid and POPOP need high laser power, since they possess a high threshold. Alpha-cyanocynnamic acid is... 

Fig. 6.12. Data obtained by the single-photon wavelength 340 nm observation wavelength timing technique using a mode-locked ion- 390 nm. Reference scattering solution argon laser that synchronously pumps a cavity- (Ludox). Number of channels 900 channel dumped dye laser. Sample solution of POPOP width 4.68 ps. Result t = 1.05 + 0.01 ns in cyclohexane (undegassed). Excitation x = 1.055.

When normal photomultipliers that exhibit a color effect (see above) are used, the compounds of Table 6.2 that have a short lifetime (e.g. POPOP, PPO) can be used in place of a scattering solution in order to remove this effect (this method is valid for both pulse and phase fluorometries). Such a reference fluorophore must... 

Figure 1.4. Illustration of the length and space-filling POPOP in zeolite L. 

Figure 1.18 shows fluorescence microscopy images of a bipolar three-dye antenna material with POPOP in the middle, followed by Py+ and then by Ox+. The different color regions that can be observed in this simple experiment are impressive. The red color of the luminescence (1) disappears, when the crystal is observed trough a polarizer parallel to the crystal axis while the blue emission disappears when turning the polarizer by 90°. This material is very stable and is easy to handle. 

Figure 1.16. True color fluorescence microscopy pictures of Py+, POPOP-zeolite L crystals of 2-pm length. (1) Specific excitation of Py+ at 470-490 nm. (2) Excitation at 330-385 nm. (3 and 4) Show the same as 2 but after observation with a polarizer. The polarization is indicated by the arrows. (See insert for color representation.)...

Figure 5.5 Scintillants. A range of organic scintiilants is available with different solubility and emission characteristics, Scintillant cocktails or mixtures contain a primary scin-tillant such as PPO and often contain a secondary scintillant which absorbs the radiation produced by the primary scintillant and re-emits it at a longer wavelength, e.g, POPOP,...

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