Wavelength, constant

The fluorescence spectra for lomefloxacin were obtained on a SLM-Aminco 4800 Spectrofluorometer. The excitation spectra were scanned as the emission wavelength was held constant at 420 nm, while the emission spectra were scanned holding the excitation wavelength constant at 350 nm. The spectra were obtained as a function of pH at a constant concentration... 

The fluorescence spectrum (emission spectrum) of a sample is obtained by scanning M2 while keeping the excitation wavelength constant. Since the efficiency of M2 is wavelength dependent, and the detector (see below) also has a sensitivity that varies with wavelength, such a fluorescence spectrum is normally uncorrected , i.e., it will depend upon the instrument as well as the sample. The correction of emission spectra is less easy to achieve than for excitation spectra, and is less often performed, so published emission spectra often vary from instrument to instrument. At least three methods are available for emission correction. A sound but tedious method is to calibrate the emission system (i.e., M2 plus the detector) with a standard light source of known emission profile. Such devices are available from NIST and other standards bodies. Comparison of the output of the fluorescence spectrometer with the certified output of the lamp then provides a correction factor at each wavelength, which can be applied to subsequent sample spectra. A related technique is to... 

Fig. 14.5. Simulated powder patterns for polymorphic pairs identical (a), different (b). Standard parameters (see Section 5.8, eqnation 5.37 copper wavelength, constant thermal factor of4A2).

Cheung A S C, Yoshino K, Freeman D E, Friedman R S, Dalgarno A and Parkinson W H 1989 The Schumann-Runge absorption-bands of 0 0 in the wavelength region 175-205 nm and spectroscopic constants of isotopic oxygen molecules J. Mol. Speotroso. 134 362-89... 

Simultaneous Cr O " and MnOj" detemiination (Ewing, 1985) is a multivariate spectrophotometric analysis that requires detemiination of a matrix of four calibration constants, one for each unknown at each of two wavelengths. 

The hydrogen atom attached to an alkane molecule vibrates along the bond axis at a frequency of about 3000 cm. What wavelength of electromagnetic radiation is resonant with this vibration What is the frequency in hertz What is the force constant of the C II bond if the alkane is taken to be a stationary mass because of its size and the H atom is assumed to execute simple harmonic motion ... 

Measurements were performed employing a Perkin Elmer X2, 5 or 12 UV-Vis spectrophotometer at 25 O.r- C. Equilibrium constants were determined by measuring the extinction coefficient at a suitable wavelength of the partially complexed dienophile (y,.hs) as a function of the concentration of... 

The Wien displacement law states that the wavelength of maximum emission, A , of a blackbody varies inversely with absolute temperature the product A T remains constant. When A is expressed in micrometers, the law becomes... 

To determine the formula for the complex between Fe + and o-phenanthroline, a series of solutions was prepared in which the total concentration of metal and ligand was held constant at 3.15 X 10 M. The absorbance of each solution was measured at a wavelength of 510 nm. Using the following data, determine the formula for the complex. 

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