Time-domain spectroscopy basic principles

Beyond imaging, CARS microscopy offers the possibility for spatially resolved vibrational spectroscopy [16], providing a wealth of chemical and physical structure information of molecular specimens inside a sub-femtoliter probe volume. As such, multiplex CARS microspectroscopy allows the chemical identification of molecules on the basis of their characteristic Raman spectra and the extraction of their physical properties, e.g., their thermodynamic state. In the time domain, time-resolved CARS microscopy allows recording of ultrafast Raman free induction decays (RFIDs). CARS correlation spectroscopy can probe three-dimensional diffusion dynamics with chemical selectivity. We next discuss the basic principles and exemplifying applications of the different CARS microspectroscopies. 

The use of nonlinear least-squares analysis is ubiquitous in the analySK of fluorescence data, pairicululy time-domain and fiequency-domain data. A usefiil introduction to the principles of least-squares analysis is found in the compact but informative book by Bevington (1969). The applications of these concepts to diverse types of fluorescence data can be found in edited volumes (Brand and Johnson, 1992 Johnson and Brand, 1994). For more basic information about statistics and spectroscopy, one can examine several introductoiy texts (Ihylor, 1982 Mark and Workman, 1991). 

A. Pifferi, A. Farina, A. Torricelli, G. Quarto, R. Cubeddu, and P. Taronia, Review Time-Domain Broadband Near Infrared Spectroscopy of the Female Breast A Focused Review from Basic Principles to Future Perspectives, /. Near Infrared Spectros., 20,223 (2012). 

The purpose of this chapter is to review ultrafast, time-resolved X-ray diffraction from liquids. Both experimental and theoretical problems will be treated. The stmcture of the chapter is as follows. Section II describes the principles of a time-resolved X-ray experiment and details some of its characteristics. Basic elements of the theory are discussed briefly in Sections III-V. Finally, Section VI presents recent achievements in this domain. The related field of time-resolved X-ray spectroscopy, although very promising, wiU not be discussed. 

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