Spectrometers entrance slit

Optimum transmission of secondary ions is achieved when the acceptance of the mass spectrometer is matched with the secondary ion beam. Figure 4a shows schematically the transfer of the secondary ion beam from the sample to the mass spectrometer entrance slit. If d. is the diameter of the area to be analyzed, the entrance slit Xwidth s) has to accept the image d + which is d + 0 1. rf"j is the virtual width of the sample point, given by = V /E where Is the initial kinetic energy and E is the field strength on the surface. This explains the desirability for high extraction fields at the sample surface). Using the Louiville theorem, we obtain... 

Block the laser beam or spectrometer entrance slit and adjust the spectrometer to an anti-Stokes shift of 1000 cm Caution Exposure of the sensitive phototube to the intense Rayleigh scattering line can seriously damage the detector. Scan the anti-Stokes spectrum from 1000 to 150 cm in the parallel polarization configuration and, using appropriate sensitivity expansion, j measure the ratio of anti-Stokes to Stokes peak heights for each band. 

The alignment of optics used for delivering the laser beam to the sample and for collecting Raman scattered radiation towards the spectrometer entrance slit is very important for the effective application of Raman spectroscopy, since Raman scattering is very weak. In conventional Raman instruments this procedure is rather... 

FIGURE 3-19. A condensing lens used to focus radiant energy on a spectrometer entrance slit. 

Optimum adjustment of the spectrometer entrance slit width. 

A simple spectrometer that we have used successfully is shown in Figure 2. Electrons from an electron microscope hairpin tungsten filament are focused with an Einzel lens onto the monochromator entrance slit, pass through the monochromator and exit slit, and are focused on the sample s surface by additional electrostatic... 

Modern XPS spectrometers employ a lens system on the input to the CHA, which has the effect of transferring an image of the analyzed area on the sample surface to the entrance slit of the analyzer. The detector system on the output of the CHA consists of several single channeltrons or a channel plate. Such a spectrometer is illustrated schematically in Fig. 2.6. 

A modern laser Raman spectrometer consists of four fundamental components a laser source, an optical system for focusing the laser beam on to the sample and for directing the Raman scattered light to the monochromator entrance slit, a double or triple monochromator to disperse the scattered light, and a photoelectric detection system to measure the intensity of the light passing through the monochromator exit slit (Fig. 7). 

A modern spectrophotometer (UV/VIS, NIR, mid-IR) consists of a number of essential components source optical bench (mirror, filter, grating, Fourier transform, diode array, IRED, AOTF) sample holder detector (PDA, CCD) amplifier computer control. Important experimental parameters are the optical resolution (the minimum difference in wavelength that can be separated by the spectrometer) and the width of the light beam entering the spectrometer (the fixed entrance slit or fibre core). Modern echelle spectral analysers record simultaneously from UV to NIR. 

The Compton profile measurements on Cu and Cu 953AI0047 were performed at ID 15b of the ESRF. Figure 1 shows the setup of the scanning-type Compton spectrometer used. It consists of a Si (311) monochromator (M), a Ge (440) analyzer (A) and a Nal detector (D). The signal of an additional Ge solid state detector (SSD) was used for normalization. ES, CS and DS denote the entrance slit, the collimator slit and the detector slit, respectively. For each sample 10 different directions were measured with approximately 1.5-2 x 103 7 total counts per direction. The incident energy was 57.68 keV for the Cu and 55.95 keV for the Cuo.953Alo.047 measurement. 

Hartmann test spect A test for spectrometers in which light Is passed through different parts of the entrance slit any resulting changes of the spectrum Indicate a fault In the Instrument. hart-man. test ... 

Atomic emission from the plasma is focused on to the entrance slit of the monochromator using a combination of convex or plano-convex lenses or a concave mirror. The combination of focusing optics, monochromator and detector is generally referred to as a spectrometer, although the heart of the device is the monochromator. A monochromator is an instrument that... 

We shall assume that the spectrometer basically consists of an entrance slit of area A focused on an exit slit at 1 1 magnification (Fig. 1). The recorded image is blurred because of diffraction and aberrations in the optics between the two slits and because of electronic blur in the readout circuit. The ultimate aim is to deconvolve or restore the spectral image so as to retrieve the spectral pattern at the entrance slit the latter pattern is called the object. 

Figure 1.14 Schematic of a 60° magnetic sector field mass spectrometer (Nier s mass spectrometer, 1940) 5, - entrance slit S2 - exit slit (H.Kienitz (ed.), Massenspektrometrie (1968), Verlag Chemie, Weinheim. Reproduced by permission of Wiley-VCH.)...

But in practice no ion emitting point (A ) exists, because mass spectrometers use slit systems (entrance and exit slits) of finite width (b and b", respectively), and so parameters b and b" are introduced to describe the defined object and image widths of the entrance and exit slits (A and A"), respectively. The ratio b"/b is defined as the so-called transverse magnification Gm of a homogeneous magnetic sector field ... 

---