Introduction to Spectroscopy - Vibrational Spectroscopy for Tissue Analysis - page 4

Table 1.1
Electromagnetic Spectrum Regions and Their Properties

Energy
(Joules/mole)

Nature of
Interaction Spectral Region Frequency (Hz) Wavelength

Radiofrequency
region

3 × 10 6 - 3 × 10 10 10 m - 1 cm 10 −3 - 10 −1 Reversal spin of

nucleus or electron

Microwave
region

3 × 10 10 - 3 × 10 12 1 cm - 100 µm 10 Rotational quantum

number of
molecule

Infrared
region

3 × 10 12 - 3 × 10 14 100 µm - 1 µm 10 3 Molecular vibration

Visible and
ultraviolet
regions

3 × 10 14 - 3 × 10 16 1 µm - 10 nm 10 5 Change of electron

distribution

X-ray region 3 × 10 16 - 3 × 10 18 10 nm - 100 pm 10 7 Change of electron

distribution

γ-ray region 3 × 10 18 - 3 × 10 20 100 pm - 1 pm 10 9 Rearrangement of

nuclear particles

that results in changes to the native biochemistry would therefore lead to
changes in the Fourier transform infrared (FTIR) and Raman spectra [8].
This topic investigates some of the most recent applications of vibrational
spectroscopy (i.e., Raman and FTIR spectroscopy) on different biological
samples, such as tissues, cells, and cell lines. The techniques can poten-
tially determine the dissimilarities of different types of cells at the molecu-
lar level. The techniques can identify the functional groups and chemical
bonds that are present in the biological tissues or/and cells. Therefore, it
is possible not only to evaluate the structure of the proteins, lipids, carbo-
hydrates, and nucleic acids that are present in a biological molecule, but
also the changes that are taking place in their chemical structure due to
the disease process, thus making it possible to monitor the progression of
the disease process and allowing prediction of the chemical pathway of the
progression.

Principles of raman Spectroscopy

Raman spectroscopy is a vibrational spectroscopic technique that is used to
optically probe the molecular changes associated with diseased tissues [9,10].
The technique is based on different types of scattering of monochromatic
light, usually from a laser in the visible, near-infrared, or near-ultraviolet
range. Light from the illuminated spot is collected with a lens and sent
through a monochromator. When the energy of an incident photon is unal-
tered after collision with a molecule, the scattered photon has the same fre-
quency as the incident photon. This is called elastic or Rayleigh scattering .
When energy is transferred from the molecule to the photon or vice versa,