1 General Overview on Vibrational Spectroscopy Applied in Biology and Medicine
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the molecule and the conduction band of the metal, and (iii) resonances within the
molecule itself [3].
vCd, RoA and ECd are applied to study enantiomers, but beside small molecules
also large and complex biopolymers e.g. proteins and dNA can be analysed. With
the help of ab initio calculations the identification of absolute configuration of the
molecule is possible. the measurements requires the use of left- and right- circularly
polarized light, the spectrometers must be very sensitive, and usually the spectra require a long accumulation. For most biomolecules, i.e. proteins and nucleic acids, the
difference in absorbance (scattering) between the two configurations is a few orders
of magnitude smaller than the corresponding unpolarized absorbance (scattering).
most of well known advantages of matrix isolation spectroscopy are related to
studies of short-lived molecules and free radicals, but also should be listed: the
elimination of hot transitions from the thermally populated vibrational states, sharpness and significantly reduced overlap of the spectral bands, the possibility to study
thermally unstable species. In the gas phase, the molecules can be observed unhindered by the environment, and very high-resolution spectra can be used to determine all of the physical properties of a molecular system [1].
1.2 Biological Application
Both IR and Raman spectroscopy can provide important information about the
composition and complexity of biological samples. First biological applications
of IR spectroscopy were limited to dried plant material and related products because of strong dipole moment of water. the development of Fourier transform
(Ft) methods pushed the usage of both spectroscopic techniques dramatically. Also
better signal-to-noise ratio and shorter time of spectrum acquisition resulted in new
applications of these methods. In particular, AtR techniques have improved rapid
IR measurements of most liquids such as edible oils, essential oils and solvent extracts of various plant tissues. high accuracy of IR measurements gives an alternative to the conventional methods such as titration and, as a result, IR is most
commonly applied for the analysis of dried or non-aqueous plant materials. on the
other hand, water has weak Raman scattering properties and consequently Raman
methods are more suitable for in situ studies of fresh plant materials. Contrary to
IR, Raman spectroscopy does not require special sample preparation and optical
transparency. Samples can be analyzed directly wet or dry and in many cases nondestructively. Although Raman scattering is weaker than IR absorption, in some
cases samples containing lower analyte concentration can be investigated. In particular, two techniques, i.e. resonance Raman and SERS, result in a significant sensitivity enhancement.
Since each functional group in a molecule contributes more or less to the spectral
output, vibrational spectra of plant material are usually very complex. the accurate
results from spectroscopic analysis can be difficult because of the fact that overlapping and mixing of various vibrational modes occur. Consequently, for many years
IR spectroscopy in the middle spectral range (mIR) was used in agricultural studies
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the molecule and the conduction band of the metal, and (iii) resonances within the
molecule itself [3].
vCd, RoA and ECd are applied to study enantiomers, but beside small molecules
also large and complex biopolymers e.g. proteins and dNA can be analysed. With
the help of ab initio calculations the identification of absolute configuration of the
molecule is possible. the measurements requires the use of left- and right- circularly
polarized light, the spectrometers must be very sensitive, and usually the spectra require a long accumulation. For most biomolecules, i.e. proteins and nucleic acids, the
difference in absorbance (scattering) between the two configurations is a few orders
of magnitude smaller than the corresponding unpolarized absorbance (scattering).
most of well known advantages of matrix isolation spectroscopy are related to
studies of short-lived molecules and free radicals, but also should be listed: the
elimination of hot transitions from the thermally populated vibrational states, sharpness and significantly reduced overlap of the spectral bands, the possibility to study
thermally unstable species. In the gas phase, the molecules can be observed unhindered by the environment, and very high-resolution spectra can be used to determine all of the physical properties of a molecular system [1].
1.2 Biological Application
Both IR and Raman spectroscopy can provide important information about the
composition and complexity of biological samples. First biological applications
of IR spectroscopy were limited to dried plant material and related products because of strong dipole moment of water. the development of Fourier transform
(Ft) methods pushed the usage of both spectroscopic techniques dramatically. Also
better signal-to-noise ratio and shorter time of spectrum acquisition resulted in new
applications of these methods. In particular, AtR techniques have improved rapid
IR measurements of most liquids such as edible oils, essential oils and solvent extracts of various plant tissues. high accuracy of IR measurements gives an alternative to the conventional methods such as titration and, as a result, IR is most
commonly applied for the analysis of dried or non-aqueous plant materials. on the
other hand, water has weak Raman scattering properties and consequently Raman
methods are more suitable for in situ studies of fresh plant materials. Contrary to
IR, Raman spectroscopy does not require special sample preparation and optical
transparency. Samples can be analyzed directly wet or dry and in many cases nondestructively. Although Raman scattering is weaker than IR absorption, in some
cases samples containing lower analyte concentration can be investigated. In particular, two techniques, i.e. resonance Raman and SERS, result in a significant sensitivity enhancement.
Since each functional group in a molecule contributes more or less to the spectral
output, vibrational spectra of plant material are usually very complex. the accurate
results from spectroscopic analysis can be difficult because of the fact that overlapping and mixing of various vibrational modes occur. Consequently, for many years
IR spectroscopy in the middle spectral range (mIR) was used in agricultural studies