Wavelength modulation

Figure Al.3.17. Modulated reflectivity spectrum of silicon. The theoretical curve is obtained from an empirical pseudopotential calculation [25], The experimental curve is from a wavelength modulation experiment from [32],...

Derivative spectra can be recorded by means of a wavelength modulation... 

Bruno Batz, Thermal and Wavelength Modulation Spectroscopy... 

Furthermore, if one uses the wavelength modulation technique, which is strictly not surface sensitive but only enhances sharp structures and as the bandwidth of a grating monochromator decreases with decreasing energy, the low frequency peak will appear broad for reasonable slit widths. The... 

Fig. 1. Schematic drawing of the wavelength modulation spectrometer setup. The spectrometer keeps the throughput (//3.6) of the monochromator through the whole...

Figure 1 shows this latest version of the experimental setup with the wavelength modulation spectrometer, where emphasis has b n put on stability of all parts. During the course of writing this paper I was Anally able to detect the low frequency metal-molecule stretch of CO/Pt(lll), as will briefly be discussed in section 4. 

Fig. 14. Preliminary infrared absorption spectra of the metal-molecule stretch mode for C Oand C Ointhec(4 x 2) structure on Pt(l 11) at 100 K recorded by a reflection wavelength modulation spectrometer. The recorded first derivative spectrum has been numerically integrated. Both spectra are reproduced in the figure.

Figure 6. SPR sensor based on ATR method and wavelength modulations (upper) and corresponding reflectivity calculated for two different refractive indices of sample (lower). Sensor configuration SF14 glass prism, 50 nm thick gold layer, sample, incident angle - 54°.

Fig. In prism-based SPR sensors with wavelength modulation and...

Direct detection of Staphylococcal enterotoxins B (SEB) is illustrated in Fig. 14 which shows binding of SEB to the wavelength-modulated SPR sensor surface coated with respective antibodies for five different SEB concentrations". Figure 15 shows the sensor response to binding after 30-minute SEB incubation and initial binding rate as a function of SEB... 

B. O. Seraphin, Electroreflectance R L. Aggarwal, Modulated Interband Magnetooptics D. F. Blossey and Paul Handler, Electroabsorption B. Batz, Thermal and Wavelength Modulation Spectroscopy 7. Balslev, Piezopptical Effects... 

A) angular modulation and (B) wavelength modulation as described by Homola et al. (2002). 

The strength of wavelength modulation spectroscopy is its relative simplicity, its main disadvantage being its sensitivity to all absorbing species in the optical path and to any fairly rapid wavelength dependence of the monochromator output or detector response. 

In summary, the three advantages of IRES over wavelength modulation photometric spectroscopy are ... 

Over conventional reflectance photometry, IRES retains advantages 1) and 2), with 3) being partially lost (the substrate contribution to A only is measurable) however, sensitivities are a factor of 10 or more lower. Polarization modulation techniques that determine only Ae, and not the corresponding dispersion property (6,J), retain advantage 1) over wavelength modulation photometry,but not advantage 2),and retain advantage 3) only in part, as above. 

In these WMS signals, the wavelength crosses the water absorption feature twice for each modulation cycle. Therefore, when water vapor is in the optical path, the amplitude modulation of the received laser power contains a periodic component having precisely twice the wavelength modulation frequency and fixed in phase relative to the wavelength modulation. 

ICP-AES=inductively coupled plasma-atomic emission spectrometry Mg(N03)3=magnesium nitrate MIBK=methylisobutyl ketone MS=mass spectrometry PIXE=proton-induced X-ray emission spectrometry XRF=X-ray fluorescence analysis WM-AES=wavelength-modulated atomic emission spectrometry... 

Fig. 80. I instrumentation for speciation of Crm and Crvl by wavelength modulation laser AAS in an analytical flame and the corresponding chromatograms obtained for deionized water. (Reprinted with permission from Ref. [257].)...

Groll H., Schnurer-Patschan C., Kuritsyn Yu. and Niemax K. (1994) Wavelength modulation diode laser atomic absorption spectrometry in analytical flames, Spectrochim Acta, Part B 49 1463-1472. 

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