Crystal Spectroscopy
Crystal Spectroscopy is a specialized technique within the broader field of spectroscopy, which involves analyzing the light emitted by objects to gather crucial information about their composition and characteristics. By utilizing one or more crystals to disperse light, scientists can break down the light into its electromagnetic spectrum, which includes both visible and invisible wavelengths such as ultraviolet and x-rays. This method allows researchers to study distant celestial bodies by examining the unique light signatures they emit, providing insights into their chemical makeup, speed, and atmospheric conditions.
The process relies on a spectrometer, an instrument that captures and analyzes the light spectrum, allowing scientists to create detailed graphs that represent the energy levels of various wavelengths. Such graphical representations are essential for deciphering complex light emissions, particularly from distant stars or phenomena like black holes. Bragg's law plays a pivotal role in crystal spectroscopy by enabling precise angle adjustments to study specific wavelengths.
The application of crystal spectroscopy has led to significant discoveries in astronomy, such as identifying elements on other celestial bodies and analyzing water presence on places like Mars and Enceladus. Beyond astronomy, this technique holds promise for Earth-based applications, including monitoring volcanic activity. Overall, crystal spectroscopy is a vital tool for expanding our understanding of the universe and the underlying principles of light.
Crystal Spectroscopy
FIELDS OF STUDY: Astrophysics; Space Technology
ABSTRACT: Spectroscopy breaks down the light emitted by an object into separate wavelengths so that the object can be studied. This study helps determine properties of the object. These include its luminescence, light absorption and reflection, and reaction to external forces, such as electricity and radiation. In crystal spectroscopy, a spectrometer passes the object’s light through a crystal with a known makeup to measure its wavelengths and analyze its characteristics. Astronomers use this data to understand the makeup of celestial bodies, especially those that cannot be studied directly.
How Spectroscopy Works
Scientists in many fields use spectroscopy to gather information about an object by studying the energy it gives off in the form of light. In astronomy, spectroscopy provides a way for scientists to learn about objects that are too far away to be studied directly.
Spectroscopy is a useful tool because scientists already know a great deal about light. Light is a form of energy that also has properties of a particle. It travels in waves and is affected by things around it. Obstacles can interrupt the travel of light. This is similar to the way water flowing along a river is affected by an encounter with a bridge support. A fast-moving river will make waves with great rippling energy. A slow river will create larger but lower energy waves. Likewise, light traveling at a higher speed has greater energy than slower-moving light. Observing the type of light waves given off by an object can help scientists understand much about the object. This includes how fast it is moving, the conditions of the atmosphere where it is located, and even its composition.
In research using crystal spectroscopy, scientists can break down the light emitted by an object into its electromagnetic spectrum of colors and wavelengths. This includes the visible colors (the rainbow seen when sunlight passes through a prism) as well as rays outside the visible spectrum. Studying the wavelengths that are invisible without special equipment (such as gamma, ultraviolet, infrared, and x-rays) allows scientists to see known objects in a new way and gather crucial information about unknown ones. It can also reveal objects that cannot be observed by sight alone. By examining an object’s light spectrum, scientists can learn about properties such as its absorption, reflection, and luminescence. Thus, with the help of a crystal spectrometer, they can determine characteristics of light emitted from a far-off celestial body.
Application of Crystal Spectroscopy
A spectrometer is an instrument calibrated to provide standard and meaningful data from the light being analyzed. In crystal spectroscopy, this instrument involves using one or more crystals of known makeup (concave, bent, or sometimes flat) to disperse the light toward a detector for study. Scientists then look at the different aspects of the light spectrum separately and record how much of each type there is. With this data they can plot a graph of the light spectrum of that particular object. Using light spectrum data from known crystals, scientists can identify the unknown chemical makeup of the light source being studied.
However, the spectra of objects can be quite complicated. This is especially true when studying distant celestial objects. A star might be giving off light from more than one source, for instance. It may be made up of a number of different chemicals or have other objects interfering with the emitted light. Scientists plot the light onto a graph to help make sense of the various types of energy given off by the object. These graphs are very useful in making sense of x-ray emissions often found coming from accretion disks around black holes. These emissions are the result of a continuous release of x-ray photons of all levels of energy.
Bragg’s law was identified in 1913 when English physicist Sir W. H. Bragg (1862–1942) and his son, Sir W. L. Bragg (1890–1971), searched for an answer to why crystal faces seemed to reflect x-rays at certain angles. In their equation, λ is the wavelength of x-rays hitting the crystal, d is the spacing of the crystal lattice or framework, and θ is the angle in degrees. Scientists apply Bragg’s law with the following equation:
nλ = 2d sinθ
Application of the Bragg’s law in crystal spectroscopy lets scientists angle the crystal to study a particular wavelength of the source object’s light spectrum.
Astronomic Spectroscopy Findings
Spectroscopic study of the universe has led to many major discoveries. The fact that elements such as hydrogen and helium that are found on Earth are also found in the sun and many other celestial bodies was the result of spectroscopic study. Scientists have uncovered the makeup of other planets using this technique.
Orbiters launched by the National Aeronautics and Space Administration used spectroscopy to confirm suspected water jets on Saturn’s moon Enceladus in 2007. It also helped identify ice-filled craters on Mars. Similar studies revealed the presence of light wavelengths suggesting the existence of hydrogen and oxygen—the makings of water—on Earth’s moon in 2009.
Spectroscopic equipment on the Hubble Telescope, James Webb Space Telescope, and other orbiters seeks to reveal the secrets of quasars as well as some of the oldest parts of the galaxy.
Importance of Crystal Spectroscopy
Due to the vastness of the universe and limitations of space travel, very little of what is known about the universe has come from direct, hands-on study. Humans have spent a few days on the moon, landed uncrewed exploratory craft on Mars, and circled other planets and moons with orbiters equipped to make observations. Thus, the information that can be gathered through spectroscopy is key to understanding the solar system and the universe beyond.
As scientists continue to refine this technique, they will be able to examine even the most distant celestial objects in greater detail. The tools planned for use in space will also have applications on Earth. For instance, scientists have been experimenting with using orbiting spectroscopic equipment to study the changes in volcanoes before, during, and after an eruption. This could lead to a better understanding of how and why eruptions happen and to more precise predictions of when they may occur.
PRINCIPAL TERMS
- absorption: the process by which the energy of an electromagnetic wave passing through matter is retained and transferred to a molecule or atom.
- luminescence: the light given off by matter that does not get its energy from the creation of heat.
- photon: an elementary particle of light that moves and has energy but lacks mass and electrical charge.
- reflection: the return of a light or sound wave to its source. The wave bounces back after interacting with a surface.
- spectroscopy: the study of the spectrum of light wavelengths emitted by atoms and molecules. This tool helps researchers determine the wavelengths of an object’s light. It can also verify the object’s velocity, temperature, and makeup.
- spectrum: the range of wavelengths that make up light, such as visible, infrared, and ultraviolet light.
- x-ray: a type of electromagnetic radiation with very short wavelengths and very high energy. X-rays are produced in space by a number of sources, including supernovas, neutron stars, and quasars.
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