Scientific terms are often used interchangeably, and scientifically accepted descriptions are continuously refined and reinterpreted, which can lead to misunderstandings in scientific knowledge. While it is impossible to completely eliminate such errors, they can be minimized by making us aware of them, gaining a better understanding of the terminology, and using careful and thoughtful scientific methods. This is certainly true when understanding spectroscopy and spectral measurement, which, although similar, are not the same. With this in mind, let us delve deeper into these terms.
SPECTROSCOPY
Spectroscopy is the study of the absorption and emission of light and other radiation by matter. It involves the separation of light (or more precisely, electromagnetic radiation) into its constituent wavelengths (spectrum), done in a manner similar to how a prism separates light into a rainbow of colors. In fact, traditional spectroscopic methods were performed using prisms and photographic plates.
Spectroscopy is the study of the absorption and emission of light and other radiation by matter. It involves the separation of light (or more precisely, electromagnetic radiation) into its constituent wavelengths (spectrum), done in a manner similar to how a prism separates light into a rainbow of colors. In fact, traditional spectroscopic methods were performed using prisms and photographic plates.
Recently, the definition of spectroscopy has been expanded to include the study of interactions between particles such as electrons, protons, and ions, as well as their interactions with other particles as a function of their collision energy.
How is SPECTROSCOPY used?
Not just a specialized, unique field, spectroscopy is indispensable in many different areas. While it provides a theoretical foundation supporting initial quantum research in radiation and atomic structure, it also has some incredible applications; Magnetic Resonance Imaging (MRI) and X-rays use a form of radio frequency spectroscopy, we measure the unique structure and physical properties of distant celestial bodies through their spectra and wavelengths, and it is even used to test for doping in sports.
Different types of spectra are distinguished by the type of radiation energy involved in the interaction. In many applications, the spectrum is defined by measuring changes in the intensity or frequency of this radiation energy. Types of spectra can also be distinguished by the nature of the interaction between energy and materials. Examples include:
ASTRONOMICAL SPECTROSCOPY
This type of spectrum primarily concerns the analysis of objects in space. From a simple spectral analysis of an astronomical object, we can measure the spectrum of electromagnetic radiation and determine its wavelength. This can inform us about the chemical composition of the object (as a factor of the spectrum and their mass), temperature, distance, and speed (using the function of wavelength and the speed of light).
ABSORPTION SPECTROSCOPY
Absorption spectroscopy involves using spectroscopic techniques to measure the absorption of radiation in matter. We can determine the atomic composition of a sample by testing the absorption of specific elements on the electromagnetic spectrum.
BIOMEDICAL SPECTROSCOPY
Biomedical spectroscopy is a type of spectrum used in biomedical science. For example, magnetic resonance spectroscopy (a specialized technique combined with magnetic resonance imaging) is often used to diagnose and study chemical changes in the brain that can cause anything from depression to physical tumors, as well as analyze the metabolic structure of tissues. This works by mapping the spectrum of wavelengths in the brain corresponding to known spectra and carefully analyzing the samples and spectral errors in those samples.
ENERGY-DISPERSIVE X-RAY SPECTROSCOPY
Energy dispersive X-ray spectroscopy (also known as EDS / EDX) is used to identify and quantify the elements found in a sample. This technique is used by the Phenom ProX Desktop SEM. It can also be used in conjunction with Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) to produce spatially resolved elemental analysis in areas with diameters as small as a few nanometers.
SPECTROMETRY
Spectrometry is the measurement of the interaction between light and matter, the reactions, and the measurement of the intensity and wavelength of radiation. In other words, spectrometry is a method for studying and measuring a specific spectrum, and it is widely used to analyze the spectra of sample materials.
Mass spectrometry is an example of a type of spectrometry, and it measures the mass in a chemical sample through the mass-to-charge ratio of its particles. This is typically done by ionizing the particles with an electron beam, then passing them through a magnetic field to separate them into different deflection stages. As the particles are separated, they are measured by an electron multiplier, and we can determine the composition of the sample through the weight of each ion. Typically, scanning electron microscopes provide options for spectrometry measurements based on the application.
Practical applications of mass spectrometry include determining isotopic ages and characterizing proteins. Autonomous mobile space exploration robots like the Mars Phoenix Lander also carry mass spectrometers to analyze extraterrestrial soil.
The history of SPECTROMETRY
Research on spectral measurement dates back to the 1600s when Isaac Newton first discovered that light converging through glass separates it into different colors of the rainbow (known as the spectrum of visible light). The spectrum itself is a clearly visible phenomenon (it creates the colors of the rainbow and produces the light you see on the surface of a puddle), but it took centuries of research to develop the study of this phenomenon into a unified field that can be used to draw useful conclusions.
Many generations of research by scientists, such as William Hyde Wollaston, led to the discovery of dark lines that seemed to be randomly placed along this spectrum. Eventually, it was determined that these were the result of the absorption of chemical substances in the Earth's atmosphere.
Simply put, because natural light filters from celestial bodies in space like the sun, it undergoes various reactions in our atmosphere. Each chemical element reacts slightly differently in this process, some reactions are obvious (elements at wavelengths of 390-700nm can be detected by the human eye) and some are invisible (such as infrared waves or ultraviolet rays, which lie outside the visible spectrum).
Since each corresponding atom can be represented by an individual spectrum, we can use the analysis of wavelengths in the light spectrum to identify them, quantify physical properties, and analyze chains and chemical reactions from within their frameworks.
Some practical ways we use the spectrum include:
We can use the unique spectrum to determine the chemical composition, temperature, and velocity of objects in space.
To screen and analyze metabolites, and improve the structure of drugs.
To measure chemicals or nanoparticles sampled through their mass-to-charge ratio using a mass spectrometer.
The difference between SPECTROMETRY and SPECTROSCOPY
Spectroscopy is the science that studies the interaction between matter and radiation energy. It is the study of the absorption characteristics of matter, or the absorption behavior of matter, when subjected to electromagnetic radiation. Spectroscopy does not produce any results; it is simply a theoretical approach to science.
On the other hand, spectrometric measurement is the method used to obtain a quantitative measurement of a spectrum. This is a practical application in which results are produced, helping to quantify, for example, absorption, optical density, or transmittance.
In summary, spectroscopy is a theoretical science, and a spectrum is a practical measurement in balancing matter at the atomic and molecular level.
SPECTROMETERS
A spectrometer is any instrument used to measure the variation of a physical property over a certain range, that is, a spectrum. This can be the mass-to-charge spectrum in a mass spectrometer, the variation of nuclear magnetic resonance frequency in a nuclear magnetic resonance (NMR) spectrometer, or the change in the absorption and emission of light with wavelength in a spectrophotometer. Mass spectrometers, NMR spectrometers, and spectrophotometers are the three most common types of spectrometers found in laboratories around the world.
Spectrometers measure the wavelength and frequency of light, while allowing us to identify and analyze the atoms in a sample that we place inside it. In its simplest form, a spectrometer works like a sophisticated form of diffraction, somewhat similar to the light game that occurs when white light shines through the small holes of a DVD or other compact disc.
Light is transmitted from a source (which has been heated to glow by heating) to a diffraction grating (like an artificial Fraunhofer line) and onto a mirror. Since the light emitted from the original source is characteristic of its atomic interactions, first, diffraction and reflection will scatter, then reflect, the wavelengths into a format that we can detect and quantify.