Slit Width, effects

The mechanical slit is placed before the detector to limit further the number of frequencies that impinge simultaneously upon it. Transfer optics may differ from one type of monochromator to another and yield different spatial spreads of the frequencies that arrive at the mechanical slit. An adjustment of the slit width effects... 

ORD techniques do not appear to be useful in the infrared. In the first place, optical rotation is a refraction phenomenon which is not easily studied within absorption bands because of slit-width effects these have given rise to spurious Cotton effects in infrared ORD Secondly, the multiplicity of bands in the middle IR would, at best, give ORD curves of incredible complexity. More telling is the failure of attempts to demonstrate that infrared bands could produce optical rotation in nearby regions of transparency it was found that optical rotation between 4000 and 2000 cm was still dominated by contributions from remote electronic transitions Background rotation of this nature would only make the observation of contributions from infrared bands difficult to discern. 

Raman lines were measured at room temperature. The finite slit width effect on the observed Raman linewidth was corrected using... 

Slit width effect is treated by Gibson in Mellon s book which also shows visible spectra of a didymium glass taken at nominal slit widths equivalent to 4 and 8 mu of spectrum, pointing out both differences in recorded transmittance and shifts of wavelengths of maximum absorption. 

Effect of the monochromator s slit width on noise and resolution for the ultraviolet absorption spectrum of benzene. The slit width increases from spectrum (a) to spectrum (d) with effective bandpasses of 0.25 nm, 1.0 nm, 2.0 nm, and 4.0 nm. 

This experiment describes a fractional factorial design used to examine the effects of flame height, flame stoichiometry, acetic acid, lamp current, wavelength, and slit width on the flame atomic absorbance obtained using a solution of 2.00-ppm Ag+. 

Figure 8.4 illustrates pressure-driven flow between flat plates. The downstream direction is The cross-flow direction is y, with y = 0 at the centerline and y = Y at the walls so that the channel height is 2Y. Suppose the slit width (x-direction) is very large so that sidewall effects are negligible. The velocity profile for a laminar, Newtonian fluid of constant viscosity is... 

Figure 2 Effect of slit-width on linearity— benzoic acid at 254 nm, 1.0 AUFS. (From Pfeiffer, C. D., Larson, J. R., and Ryder, J. F., Linearity testing of ultraviolet detectors in liquid chromatography, Anal. Chem., 54,1622,1983. Copyright American Chemical Society Publishers. With permission.)...

Experimentally, several precautions must be taken if reliable Raman data are to be obtained from solution studies. Firstly, the instrumental slit-width should be appreciably smaller than the half-width of the band to be studied. This means that slits wider than 2 cm-1 are to be avoided. Secondly, photolytic decomposition of the sample and local boiling of the solvent have also to be avoided. Careful choice of laser frequencies, use of a low incident power and, if necessary, sample spinning are indicated. The need for a relatively high solute concentration usually means that there is little choice of solvent. Particularly for coloured samples the presence of a vestigal resonance Raman effect must be tested by measurements with a variety of... 

Spectra were run on a Perkin-Elmer model 125 grating spectrophotometer at room temperature, ignoring the heating effect of the IR beam. Reference beam attenuation was used. The spectral slit width was less than 3 cm-1 in the region 1600-1400 cm-1. Optical density measurements were carried out as previously described (19). 

We are baffled as to the cause of the discrepancy between the calculated and measured intensity curves. The mathematics of the calculated curve needs to be refined to include the width of the slit above the rotor, which we had assumed to be negligible. Perhaps the effect of changing the slit width and the focus plane in the cell should be examined. Based on the good results obtained from sedimentation equilibrium experiments, we believe that the SIT vidicon, MIA electronics, and our software controlling the gathering of data are all behaving properly, but perhaps there are still problems to be solved. 

Figure 2-7 Raman spectra of CCI4 (488.0-nm excitation) obtained under different conditions using a Spex Model 1403 double monochromator equipped with 1,800 grooves/mm gratings and a Hamamatsu R928 photomultiplier, (a) The effect of spectral bandpass (0.2-cm-1 increments per data point), (b) The effect of size of increments between the data points (1-cnT1 slit width accumulation time for all spectra was 1 second per data point.)...

Optimization in Flame AAS Source-related Parameters Effect of Lamp Current Effect of Lamp Warm Up Time Lamp Alignment Lamp Deterioration Choice of Lamp Atomizer-related Parameters Choice of Atomizer Effect of Fuel-to-oxidant Ratio Optimization of Burner Position Burner Design, Warm Up, and Cleanliness Gas Flow Stability Monochromator-related Parameters Choice of Slit Width Choice of Wavelength Optimization in Flame AFS Source-related Parameters Lamp Operating Parameters Lamp Alignment Atomizer-related Parameters Monochromator-related Parameters Optimization in Flame AES... 

With metastable ions, the isotope effect Ij/In is obtained from metastable ion abundances. The abundance is given by the area under the metastable peaks after the peak has been deconconvoluted to remove the broadening effect of finite slit widths and other factors. The usual procedures adopted in practice are either to work with narrow slits, determine peak areas and neglect deconvolution, or to work with wide slits and measure peak heights. 

In a study of the porosity of alumina-pillared montmorillonites (Al-PILCs), Zhu et al. (1995) have obtained values of the mean slit-width of 0.8-0.9 nm from the volume/surface ratio. In this case, the nitrogen adsorption values were in agreement with the corresponding dm values of c. 0.8 nm. However, effective micropore volumes obtained from the nitrogen isotherms and from water sorption data were significantly different and it was suggested that the density of the sorbed water was lower than that of liquid water. 

The concentration of benzenediazoninm ion can be determined by the absorbance at wavelengths between 295 and 325 nm. Below 295 nm, prodncts of the reaction prodnce interfering absorption and above 325 nm, the molar absorption coefficient is too small to permit effective measnrement of changes in the benzenediazoninm ion concentration." The absorbance will be measnred nsing a snitable spectrophotometer such as a Beckman model DU-20 UV detailed instrnctions for operating the instrnment will be provided in the laboratory. A wavelength of 305 nm shonld be nsed, with a slit width of 0.3 mm. Make two absorbance readings on each sample. 

Figure 2-12. Effect of slit width on the resolution of a recording spectrophotometer. (From R. L. Manning, Ed., Introduction to Spectroscopy, Pye Unicam Ltd., Cambridge, England, 1969.)...

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