Single Raman

Fig. 6.2. Illustration of the frequency-time dependences of pump and Stokes pulses in three different CRS excitation pulse schemes and their corresponding spectral resolution of Raman shifts. A Using a pair of transform-limited femtosecond pulses of broad spectral and narrow temporal widths results in a broad bandwidth of Raman shifts that exceeds the line width of a single Raman resonance. B Using transform-limited picosecond pulses of broad temporal and narrow spectral width readily provides high spectral resolution matching the Raman resonance line width to be probed. Selection of a Raman resonance shifted by AQr is achieved by tuning the frequency of one of the laser beams by the same amount. C Spectral focusing of a pair of identically linear chirped pump and Stokes femtosecond pulses results in a narrow instantaneous frequency difference in the CRS process, thus also providing narrow-bandwidth CRS excitation. Selection of a Raman resonance shifted by AQr is achieved by adjusting the time delay At between the pulses. Shifted pulses in (B) and (C) are depicted hatched...

For single yeast cell investigations it is not sufficient to characterize a yeast cell by means of a single Raman spectrum equivalently to the bacterial analysis described above. Yeast cells as eukaryotes exhibit in contrast to... 

With only a single Raman-active vibration, there is no question that the 122 cm mode corresponds to R Eg), On the other hand, there are inconsistencies among the various IR measurements. The transmission measurements of Richter et al [67] on single crystals show absorption bands at 88 cm and... 

When applied to the study of phase transformations during indentation, Raman spectroscopy drastically extends the electron microscopy results. Raman spectra indeed reveal amorphous silicon within the indentation area [64, 116] however, they also indicate that the formation of a-Si strongly depends on the experimental conditions [64]. Figure 17 shows the Raman spectra obtained from various points around Rockwell indentations in silicon. The original Si-I phase is observed outside the contact area, which is confirmed by a single Raman line at 520 cm (Fig. 17a). In contrast, the Raman spectra taken from the indentation area look... 

In stimulated Raman scattering the strongest Raman transition will have the largest gain and reaches threshold before the other transitions can develop. Just above threshold we therefore expect only a single Raman line in the stimulated Raman spectrum, while at higher pump powers more lines will appear. 

In the majority of laboratory cases, a Raman-shift sample can be placed at the sample position for calibration purposes. After primary wavelength calibration, a single Raman-shift band, if stable and well known (e.g., the 801-cm line of cyclohexane), can be used to determine a laser shift. 

A single Raman analyzer using imaging probe heads allows data to be simultaneously or sequentially collected on multiple channels, depending on how the laser is provided to the various channels. There are three approaches ... 

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