Spectroscopy may be broadly defined as the study of the interaction between matter and radiation. What makes spectroscopy truly interesting is that it’s arguably the most widely applied study method in modern science. Experimental spectroscopic studies have been central to the development of quantum mechanics, and they included the explanation of Blackbody Radiation, Photoelectric Effect and Niels Bohr's explanation of atomic structure and spectra. Since atoms and molecules have their own unique spectra response, spectroscopy can be used in Applied Chemistry to detect, identify and quantify information about particles and hence distinguish one type of matter from another. This fundamental benefit of spectroscopy has made it invaluable for Biotechnology and Life Sciences.
Expressed mathematically, spectroscopy refers to the measurement of radiation intensity as a function of wavelength. However, it can be divided into multiple types based on the type of radiative energy, and the nature of interaction between the matter and energy. In Laser Spectroscopy, researchers train a laser beam on a sample that yields a characteristic light which can be analyzed by a spectrometer. Laser Spectroscopy can, in turn, be divided into different types based on the type of laser used, and the atom's response that is studied.
In Laser-Induced-Breakdown Spectroscopy (LIB-S), a sample is excited with intense laser pulses and the emitted light is analyzed, which generally falls in the visible or infrared spectral region, i.e. having wavelengths longer than that of the pump source. LIBS is ideal for sample analysis as it doesn't require sample preparation, and generally, removes less than 1 gram of material during laser ablation. In Raman Spectroscopy, a substance is irradiated with a narrow-band light at a high optical power to detect the weak emission lines which arise from spontaneous or stimulated Raman Scattering1. The spectrum of Raman Scattered light contains information about molecular vibrations, and helps identify key properties of the material – such as wavenumber scale for example, which is essential in pharma-applications.
The past few years have seen a surge in Biotech applications that use laser spectroscopy. Raman Spectroscopy in conjunction with dynamic light scattering techniques determines stability and structure of proteins, essential for developing drugs. Another fascinating Life Science application with Near Infrared Spectroscopy is the diagnosis of neonatal brain injury. LIBS is emerging as a tool of choice to determine inorganic composition of biomass, prior to converting biomass into hydrocarbon fuels. A newly developed Raman Imager is 1000 times faster than conventional Raman microscopes, and uses vibrational spectroscopic technology to get near real-time images of organs to detect tumors and observe cell activity.
These are just a few of the advanced biotechnology applications that have benefited from using laser spectroscopic techniques. As methods and associated technology advances, we can only expect to learn about many more life science applications being enabled by this technique.
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