Dispersion, reciprocal linear

Spectrometer ARL 3400 C Quantovac 1 m Paschen-Range monuing grating ruled 1080 lines mm"1, 0.309 nm mm-1 reciprocal linear dispersion (3rd order). Primary slit width 20 pm, secondary slit 50 pm, Hamamatsu R-306 photomultiplier tube... 

The usual measure of how well a grating separates individual wavelengths is given by the reciprocal linear dispersion, in angstroms per millimeter, as follows ... 

These tubes have been employed with both one- and two-dimensional dispersive systems. For example, Harber and Sonnek (43) described an electronic scanning spectrometer based on an image-dissector photomultiplier in conjunction with a onedimensional dispersive system. Their system used a 12.7 cm Czerny-Turner mount with a reciprocal linear dispersion of... 

Exposure 20 sec at 5 amp followed by 130 sec at 15 amp, continuous burn Atmosphere 70% argon -j- 30% oxygen 6.6 L/min flow rate with top of Helz jet nozzle 2 mm below top of electrode Wavelength range 2300-4700 A first order Grating 600 groove/mm 5 A/mm reciprocal linear dispersion Slit 25 m wide X 2 mm high Filter 47% transmission neutral-density filter... 

Dispersion. The linear dispersion (in millimeters per nanometer) described above is often converted to reciprocal linear dispersion dX/dl, units of nm/mm) when stated in the manufacturer s literature. It describes how much of the spectrum (in nanometers) is covered in a unit of focal plane. If... 

The reciprocal linear dispersion of the single spectrograph in Figure 8.3 is given by ... 

Table 8.1. Reciprocal Linear Dispersion for Several Single Spectrograph Designs...

The subscript 1500 is the reciprocal linear dispersion at a Raman shift of 1500 cm (approximately the center of the spectrum), ITo is the total detector width and Nc is the number of channels along the wavelength axis. Combining with Eq. (8.6) (and assuming m = 1, cos0 = 1), yields... 

The angular dispersion and the theoretical resolving power R0 are related as d2/dX = Rq/ D. where D is the width of the monochromatic beam where it exits the dispersive element. The reciprocal linear dispersion is given as ... 

Spatial resolution is one channel which is typically 25 ym wide. Spectral resolution is the product of the channel width and the reciprocal dispersion of the spectrometer. For example, a spectrometer with a focal length of 0.25 m and grating of 152.5 grooves/mm typically produces a reciprocal linear dispersion of 25 nm/mm. Therefore a 25 ym channel will cover 0.64 nm. A 305 g/mm grating used with the same spectrometer would produce a resolution of 0.32 nm/channel. 

Spectrometers 1) Jarrell-Ash, Model 78-466, 1 meter f/8.7, Czerny-Turner mount with a 1180 g/mm grating blazed at 250 nm, reciprocal linear dispersion of 0.825 nm/mm (0.0206 nm/diode). Entrance slit width 20 um, height 2 mm. 2) McPherson, Model 2051, 1 meter, f/8.7, Czerny-Turner mount with a 1800 g/mm holographic grating blazed at 200-700 nm reciprocal linear dispersion of 0.0138 nm/photodiode, entrance slit 20 um, height 2 mm. 

Wavelength Calibration And Spectral Resolution. The wavelength calibration accuracy of the SPD depends, in principle, only on the corresponding accuracy of the spectrometer s reciprocal linear dispersion. In this study, the wavelength-to-diode calibration was proven adequately linear to determine wavelength to within +0.02 nm over the entire 20 nrn spectral window (1024 diodes) of the array, from any pair of known spectral lines. 

It is therefore essential that the user determines the effect of this "array discretness" on the accuracy of determination and accordingly set the reciprocal linear dispersion of the spectometer. Thermal insulation and/or control of the spectrometer SPD system should also be considered, because thermal expansion may reduce the accuracy of the diode-to-wavelength calibration. 

The spectral resolution of a detector is defined here as equal to its spatial resolution (in urn ) times the reciprocal linear dispersion of the spectrometer (in nm/um ). It was measured to be 1.5 - 2.5 and 2-4 times poorer for the SPD and SIT, respectively, compared to that of a PMT. All measurements were performed with the same spectometer, utilizing 20 urn slit widths. Because, the proximity focused, microchannel plate (MCP) intensi-fier broadens the line images, the spectral resolution of the ISPD was found to be significantly worse than that of the SPD. Peak widths measured at half maximum intensity were four diodes wide even when only a single diode width was illuminated. 

Bv subsliluting hi ii ition 7-7 into riqiiaiion 7- > we have the reciprocal linear dispersion l[Pg.185]

A giatfng monochromator wiih a reciprocal linear dispersion of 1.2 nm/mm i.s to be used to separalc the sodium lines at 5SS.9950 nni and. 89.5924 nni. In the ory. what slit width would be required ... 

Calculate the theoretical reciprocal linear dispersion of an echclie grating with a focal length of O.h. i m. a groove density of 120 grooves/mm. and a diffraction angle of 6.V"26 when the diffraction order is (a) 30 and (b) 90,... 

By the same token, an important criterion of monochromator performance is reciprocal linear dispersion, commonly expressed in Ang-stroms/millimeter. If the reciprocal linear dispersion of a given monochromator is, say, lOA./mm., then at a slit width of 1 mm., the resolution of the unit is lOA. For best energy, the reciprocal linear dispersion... 

Dispersion of a Grating Monochromator. The resolution of a monochromator measures its ability to separate adjacent wavelengths from each other. Resolution is related to a useful quantity called the reciprocal dispersion, or reciprocal linear dispersion,... 

The reciprocal linear dispersion dX/dx) is the function of the geometric slit width S) and spectral bandpass (AA ,) of the monochromator ... 

The reciprocal linear dispersion for a grating is nearly constant over the entire wavelength region and it is dependent on the number of grooves per unit width, spectral order, and the focal length of the collimator. The resolution of a grating is a function of spectral order (m) and the total number of grooves N) ... 

AAS measurements are almost exclusively carried out in the first order, and a good grating has 2000 to 3000 grooves mm. The reciprocal linear dispersion of 1 nm mm or less can easily be obtained with the usual focal lengths employed. Comparable reciprocal linear dispersions are achieved with a conventional prism monochromator only in the far UV region, while in the near UV and visible regions grating monochromators are superior. 

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