Spectroscopy spectrometer, schematic

Atomic emission spectroscopy is very similarly to atomic absorption spectroscopy. The difference between these methods can be seen from their names. Emitted light of the atom under analysis is analyzed by atom emission spectroscopy. The schematic for the atomic emission spectrometer is very similar to that for atomic absorption spectrometer. The schematic for the atomic emission spectrometer is presented in Figure 2.58. 

A MBER spectrometer is shown schematically in figure C1.3.1. The teclmique relies on using two inhomogeneous electric fields, the A and B fields, to focus the beam. Since the Stark effect is different for different rotational states, the A and B fields can be set up so that a particular rotational state (with a positive Stark effect) is focused onto the detector. In MBER spectroscopy, the molecular beam is irradiated with microwave or radiofrequency radiation in the... 

Fig. 4.21. Schematic diagram of spectrometer arrangements for wavelength-dispersive and energy-dispersive X-ray spectroscopy (WDXS/EDXS) in electron microscopy.

We use laser photofragment spectroscopy to study the vibrational and electronic spectroscopy of ions. Our photofragment spectrometer is shown schematically in Eig. 2. Ions are formed by laser ablation of a metal rod, followed by ion molecule reactions, cool in a supersonic expansion and are accelerated into a dual TOE mass spectrometer. When they reach the reflectron, the mass-selected ions of interest are irradiated using one or more lasers operating in the infrared (IR), visible, or UV. Ions that absorb light can photodissociate, producing fragment ions that are mass analyzed and detected. Each of these steps will be discussed in more detail below, with particular emphasis on the ions of interest. 

Fig. 3.19 Schematic illustration of the measurement geometry for Mossbauer spectrometers. In transmission geometry, the absorber (sample) is between the nuclear source of 14.4 keV y-rays (normally Co/Rh) and the detector. The peaks are negative features and the absorber should be thin with respect to absorption of the y-rays to minimize nonlinear effects. In emission (backscatter) Mossbauer spectroscopy, the radiation source and detector are on the same side of the sample. The peaks are positive features, corresponding to recoilless emission of 14.4 keV y-rays and conversion X-rays and electrons. For both measurement geometries Mossbauer spectra are counts per channel as a function of the Doppler velocity (normally in units of mm s relative to the mid-point of the spectrum of a-Fe in the case of Fe Mossbauer spectroscopy). MIMOS II operates in backscattering geometry circle), but the internal reference channel works in transmission mode...

Figure 5.3 Schematics of a typical dispersive spectrometer. After Williams [7]. From R. Williams, Spectroscopy and the Fourier Transform, VCH Publishers, New York, NY. Wiley-VCH, 1996. Reproduced by permission of Wiley-VCH...

Although there are a variety of wavelength selection methods available, the vast majority of Raman instruments utilize either dispersive or Fourier transform spectrometers. These are shown schematically in Fig. 1.6. The high throughput and spectral resolution obtainable from these instruments make them obvious choices for Raman spectroscopy however, each has specific strengths and drawbacks which make them more suitable in specific applications. 

Fig. 1.5. Schematic of a gamma-ray energy spectrometer for Doppler broadening studies. The signal from the detector pre-amp is processed by spectroscopy and biassed amplifiers (SA and BA respectively) before being recorded in the multichannel analyser (MCA).

Fourier transform (FT) IR spectroscopy is one of several nondispersive optical spectroscopies based on interferometry. A two-beam interferometer first proposed by Michelson is the basis of most modern FT-IR spectrometers, as exemplified by the schematic of the Bruker Equinox 55 spectrometer (Bruker Optik, Ettlingen, Germany) in Fig. 2. Simply described, the interferometer comprises a beam splitter and two mirrors. A collimated beam of IR energy is split at the beam splitter into equal halves. Half of the energy travels through the beam splitter to one of the mirrors, which is positioned at a fixed distance away from the beam splitter. The reflected beam travels perpendicular to the incident beam to a moving mirror. IR radiation reflects off the fixed and moving mirrors and recombines at the beam splitter. The recombined IR beam projects from the interferometer towards the detector on an optical path perpendicular to the source beam. 

Electron spin resonance (e.s.r.) spectroscopy, applied to free radicals in condensed phases, is a long established technique with several commercially available spectrometers. The gas phase applications we will describe have little in common with condensed phase studies, and are much more a part of rotational spectroscopy. However, the experimental methods used for condensed phase studies can be applied to the study of gases with rather little change, so it is appropriate first to describe a typical microwave magnetic resonance spectrometer, as illustrated schematically in figure 9.1. 

Figure 9.39 Schematic representation of the diffuse-reflection measurements with a single-element detector FT-NIR spectrometer. Reproduced with permission from Ref [68] 2008, Society for Applied Spectroscopy.

The infrared reflection-absorption spectroscopy was performed on a Bruker IFS 66 spectrometer (Karlsruhe, Germany) equipped with a MCT detector and a modified external reflection attachment P/N 19650 of SPECAC (Orpington, UK). This included a miniaturized Langmuir-trough, permitting thermostatic measurements. An extensive description of the method can be found in Gericke et al. (1993). The IRRAS set-up as well as the experimental approach can be inferred from the schematic sketch shown in Fig. 2. 

Figure 11.17 Schematic diagram of the inductively coupled plasma/mass spectrometer interface. From Dean, J. R., Atomic Absorption and Plasma Spectroscopy, ACOL Series, 2nd Edn, Wiley, Chichester, UK, 1997. Reproduced with permission of the University of Greenwich.

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