Fourier transform spectroscopy fundamentals

Smith, B.C. (1995) Fundamentals of Fourier Transform Spectroscopy. Boca Raton, FL CRC Press. 

If I (5) is other than a few discrete narrow lines, the tool to evaluate / (5) from I[s) is the Fourier transform, where I ) is the interferogram measured with a two-beam (Michelson) interferometer. This is the fundamental idea of Fourier transform spectroscopy. We have left aside the question of whether the Fourier integral Eq. (2.12) exists and whether it is meaningful or not. For the mathematical requirements on I (s), the reader is referred to the literature 34). it is sufficient to say here that, for all physically and experimentally reasonable interferograms I s), these requirements are usually met. 

The Reader It is assumed that the reader understands the fundamental principles of pulse Fourier transform spectroscopy (PFT) and is proficient in using the MS-Windows operating system and Windows based programs. The references at the end of section 1.4 list both introductory and comprehensive texts on the main principles of NMR spectroscopy. Furthermore the reader should be familiar with computer environments, as working on a spectrometer inevitable requires computer management skills. 

The fundamentals of Spectro-Spatial Interferometry (Mariotti and Ridgway 1988), also called Double Fourier Modulation (DFM) or Multi-Fourier Transform Spectroscopy (Ohta et al. 2007, 2006), are presented here and provide the background for the understanding of the following chapters. 

PH2D, PHD2. The frequency of the P-H stretching vibration in PHD2, v = 2323.81 cm" was determined by Fourier transform spectroscopy and used together with the overtone 2v = 4563.26 cm" to derive co(P-H) = 2408.17 cm" treating the P-H unit as a diatomic molecule [12]. - For the fundamental frequencies of the species in solid phases, see p. 192. 

Similar spectral techniques as discussed for macroscopic tumour imaging can be employed for fluorescence microscopy. Confocal and two-photon-induced fluorescence microscopy [10.210], and imaging Fourier transform spectroscopy [10.211] are all valuable techniques for studies at the cellular level. Related to this field is the optical trapping of ceils with focused laser beams optical tweezers), which relies on gradient forces of the same kind as discussed in Sect. 9.8.5. Trapped cells and polymer strings can be manipulated in many ways to enable fundamental studies to be conducted [10.212]. 

Collision-induced vibrational relaxation was studied on vibrationally excited NH(X produced by pulsed electron impact on N2-H2 or N2-H2-Ar gaseous mixtures time-resolved IR Fourier transform spectroscopy was used to observe the v = 3 2, 2 1, and 1 0 fundamental band emission (2500 to 3400 cm ) which allowed the time-dependent vibrational populations to be determined. The following rate constants for v v-1 transitions, were derived at room temperature for the collision partners N2, Ar, and H2 [1] ... 

Comprehensive coverage of all fundamental aspects of Fourier transform infrared spectroscopy. 

The experimental configuration of the pump-probe experiment is similar to Ref. [5]. A home built non-collinear optical parametric amplifier (nc-OPA) was used as a pump, providing Fourier-transform-limited 30 fs pulses, which could be spectrally tuned between 480-560 nm. In all experiments white-light generated in a sapphire crystal using part of the fundamental laser (800 nm), was used as probe light. In the pump-probe experiments the pump was tuned to the S2 0-0 band for carotenoids with n>l 1. In the case of M9, it was not possible to tune the nc-OPA to its 0-0 transition, and hence another nc-OPA tuned to 900 nm was frequency doubled and used for excitation. In addition to conventional transient absorption pump-probe measurements, we introduce pump-deplete-probe spectroscopy, which is sensitive to the function of an absorbing state within the deactivation network. In this technique, we... 

Fourier transform methods have revolutionized many fields in physics and chemistry, and applications of the technique are to be found in such diverse areas as radio astronomy [52], nuclear magnetic resonance spectroscopy [53], mass spectroscopy [54], and optical absorption/emission spectroscopy from the far-infrared to the ultraviolet [55-57]. These applications are reviewed in several excellent sources [1, 54,58], and this section simply aims to describe the fundamental principles of FTIR spectroscopy. A more theoretical development of Fourier transform techniques is given in several texts [59-61], and the interested reader is referred to these for details. 

One of the major advances in the past decade has been the maturation of the electronic revolution. This has had its effect on surface spectroscopy, with regard to instrumentation for transmission IR, but particularly for sensitivity gains that have made reflectance techniques the preferred alternative for fundamental studies. In the transmission mode, the commercial development of the Fourier transform IR spectrometer has led to significant advantages in the determination of the vibrational spectra of adsorbed species. This is covered in the chapter by Bell. 

The Fourier transform Raman spectrometer is constructed around an interferometer (see Figure 4.20) [57], Normally, a continuous wave Nd YAG laser (1064nm) is used for the sample excitation. In relation to the sample arrangement inside the spectrometer, there are two fundamental geometries in which a sample is tested in Raman spectroscopy, that is, the 90° geometry, where the laser beam... 

The fundamental principles of Fourier-transform, n.m.r. spectroscopy have been described in books and reviews.13-17... 

The IR and Raman spectra of partially hydrated proteins are a rich source of fundamental information on both water and protein species, owing to the sensitivity of vibrational modes to hydrogen bonding. The similar chemistry of water—water and water—peptide interactions requires that there be great accuracy in spectroscopic measurements of the hydration process. Since the review of the field by Kuntz and Kauz-mann (1974), the Fourier transform technique for IR and the tunable laser for Raman spectroscopy have offered important improvements in methodology. 

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