Microspectroscopy and imaging

Principles and Characteristics Infrared microspectroscopy can be considered as the coupling of a microscope to an infrared spectrometer. Another definition of IR microspectroscopy is the study of how infrared radiation interacts with microscopic particulates. Indeed, diffraction, refraction, reflection, and absorption effects play a much more important role in microspectroscopy than in its macroscopic counterpart. Infrared microscopy 

There are three types of IR microspectroscopy maps point, line, and area. A point map provides several different areas of a sample to be analysed consecutively, but the spectra are not related to each 

Single element detector Point-by-point analysis Line and area infrared maps Ante) or manual control ATR and grazing angle Visible image capture 2D and 3D graphics 

In conventional IR microscopy, diffraction of the long wavelength radiation (5-12 /xm) limits the spatial resolution to no better than a few micrometres in practice about 10 fxm. Expanding IR investigations to below the diffraction limit requires the use of more specialised approaches, such as near-field microscopy or scanning probe technology [301]. 

The optical requirements for an IR microscope include (i) exact positioning of the sample (ii) spatial isolation of the sample from a larger matrix in the IR beam and (Hi) capability to function in both the visible and the infrared spectral regions. For infrared microspectrometry, a thermal emission source is generally used. Fourier transform spectrometers use interferometers as an effective means to resolve photon energies. Mercury cadmium telluride (MCT) detectors have the sensitivity and speed needed for FTIR spectrometers. The use of synchrotron radiation dramatically improves infrared microspectroscopy and has the power to analyse and map samples at high resolution. SR sources have transformed the IR microspectrometer into a true IR microprobe, providing IR spectra at the diffraction limit. Optics and performance of a /uF llR interfaced with SR were described [423]. Some 15 synchrotron beam lines are equipped with IR microscopes. 

---

Imura, K. and Okamoto, H. (2008) Development of novel near-field microspectroscopy and imaging of local excitations and wave fimctions of nanomaterials. BuU. Chem. Soc.Jpn., 81, 659-675. 

Fisz JJ (2009) Another treatment of fluorescence polarization microspectroscopy and imaging. J Phys Chem A 113 3505-16... 

Zhang, G., Moore, D.J., Mendelsohn, R. and Flach, C.R. (2006) Vibrational microspectroscopy and imaging of molecular composition and structure during human comeocyte mamration. 

Wetzel, D.L. (2008) Biomedical Applications of Infrared Microspectroscopy and Imaging by Various Means, in Biomedical Vibrational Spectroscopy (eds P. Lasch and J. Kneipp), John Wiley Sons, New York, pp. 

L. Miller and R. J. Smith, Synchrotrons versus globars, point-detectors versus focal plane arrays Selecting the best source and detector for specific infrared microspectroscopy and imaging applications, Vib. Spectrosc., 2005, 38, 237-240. 

The technique of mid-IR microspectroscopy and imaging has great potential for the rapid and reliable identification of tissue structures not only for scientific research purposes but also in a real clinical set-up. The standardisation of the data acquisition and the assessment of the quality of the spectra constitute key factors for the successful transfer to elinical application. Furthermore the problem of overfitting and the role of independent validation have been discussed. In this chapter we also exemplified the question of standardisation of the hyperspectral image acquisition protocol and demonstrated how the... 

A. V. Feofanov, A. 1. Grichine, L. A. Shitova, T. A. Karmakova, R. 1. Yakubovskaya, M. Egret-Charlier, and P. Vigny, "Confocal Raman microspectroscopy and imaging study of theraphthal in living cancer cells," BiophysicalJoumal, vol. 78, pp. 499-512,2000. 

---