- What is spectrum?
- What is electromagnetic spectrum?
- Types of spectrum
- What is emission spectrum?
- What is continuous emission spectrum?
- What is line emission spectrum?
- What is band emission spectrum?
- What is absorption spectra?
- What is continuous absorption spectrum?
- What is line absorption spectrum?
- What is band absorption spectrum?
- Emission spectrum vs absorption spectrum
A spectrum is simply a chart or a graph that depicts the intensity of light emitted across a range of energies. Have you ever looked at a spectrum? Probably. Rainbows are beautiful creations of nature. The sun’s rays are dispersed as they pass through raindrops, revealing their various colors. These different colors are just the way, our eyes perceive radiation with slightly different energies. Spectroscopy can help scientists to understand how an object, such as a black hole, neutron star, or active galaxy, produces light, how fast it moves, and what elements it is made of. Spectra can be created for any light energy, from low-energy radio waves to extremely high-energy gamma rays. In this article, we will learn about the different types of spectrum.
Each spectrum contains a wealth of information. For example, there are numerous mechanisms by which an object, such as a star, can produce light. Each of these mechanisms has a distinct spectrum. Each element in the periodic table can exist in gaseous form, producing a series of bright lines that are unique to that element. Hydrogen will not resemble helium, which will not resemble carbon, which will not resemble iron… and so on. As a result, astronomers can deduce what kinds of things are in stars based on the lines in the star’s spectrum. This type of research is known as spectroscopy. The science of spectroscopy is quite complex. Astronomers can determine not only the element, but also the temperature and density of that element in the star, using spectral lines.
What is spectrum?
Spectrum is defined as a band of colors produced by the separation of light components due to their different degrees of refraction according to wavelength, as seen in a rainbow. A spectrum is used to categorize that it can be categorize in terms of its position on a scale between two extreme or opposite points.
The spectral lines can also tell us about the magnetic field of stars. The width of spectral line can tell us how fast the material is moving. This teaches us about the winds in the stars. We can deduce that the star is orbiting another star if the lines shift back and forth. This allows us to calculate the star’s mass and size. We can learn about the physical changes in the star by observing how the lines grow and fade in strength. Spectral data can also tell us about the material that surrounds stars. This material could be falling onto the star from an accretion disk, which is a doughnut-shaped disk that surrounds the star. These disks frequently form in the vicinity of a neutron star or black hole.
What is electromagnetic spectrum?
Electromagnetic energy travels in waves and covers a wide range of wavelengths, from very long radio waves to very short gamma rays. Only a small portion of this spectrum, known as visible light, can be detected by the human eye. A radio detects a different part of the spectrum, while an x-ray machine detects yet another. Electromagnetic energy is used when you tune your radio, watch TV, and send a text message, or pop popcorn in a microwave oven. Every hour of every day, you rely on this energy. The world you know would not exist without it.
The entire distribution of electromagnetic radiation according to frequency or wavelength is referred to as the electromagnetic spectrum. Despite the fact that all electromagnetic waves travel at the speed of light in a vacuum, they do so at a wide range of frequencies, wavelengths, and photon energies. The electromagnetic spectrum includes all electromagnetic radiation and is divided into many sub ranges, which are commonly referred to as portions, such as visible light or ultraviolet radiation. The various portions have different names due to differences in the emission, transmission, and absorption of the corresponding waves, as well as their various practical applications.
White light, also known as visible light can be easily separated into its constituent colors, yielding a well-known result: the rainbow. All we need to do is use a slit to direct a narrow beam of light toward a prism. This apparatus is a basic spectrometer. The resulting rainbow is a continuous spectrum that demonstrates the various light energies (from red to blue) present in visible light. However, the electromagnetic spectrum includes more than just visible light. It encompasses all light energies, from low-energy radio waves to microwaves, infrared, optical light, ultraviolet, and very high-energy X-rays and gamma rays.
Types of spectrum
When white light strikes a prism in a spectrometer, the prism deviates the waves of different wavelengths in different directions. The image obtained in the telescope’s field of view is made up of a series of colored images of the slit. A spectrum is a type of image like this. When the slit is illuminated with light from a sodium vapor lamp, two images of the slit in the yellow region of the spectrum are obtained. These are sodium emission lines with wave lengths of 5896 Ao and 5890 Ao. This is referred to as the sodium spectrum.
The spectra obtained from various bodies can be divided into two categories: emission spectra and absorption spectra.
What is emission spectrum?
The spectrum of frequencies of electromagnetic radiation emitted by an atom or molecule transitioning from a high energy state to a lower energy state is referred to as the emission spectrum of a chemical element or compound. The emitted photon’s energy equals the energy difference between the two states. Each atom has a large number of possible electron transitions, each with its own energy difference. An emission spectrum is a collection of different transitions that result in different radiated wavelengths. The emission spectrum of each element is distinct. As a result, spectroscopy can be used to identify elements in unknown matter. Similarly, the emission spectra of molecules can be used in chemical analysis of substances.
The emission spectrum is obtained by examining the light emitted directly from a source with a spectrometer. Every source emits a distinct emission spectrum. There are three types of emission spectrum.
- Continuous spectrum
- Line spectrum
- Band spectrum
What is continuous emission spectrum?
It is one of the types of spectrum that are made up of unbroken luminous bands of all wavelengths containing all colors ranging from violet to red. These spectra are only affected by the temperature of the source and are unaffected by the source’s characteristics. Continuous spectra are produced by incandescent solids, liquids, carbon arc, and electric filament lamps, among other things.
What is line emission spectrum?
Line spectra is one of the types of spectrum that are defined by sharp lines with distinct wavelengths. It is a property of the emitting substance. It’s used to figure out what kind of gas you’re dealing with. Atoms in the gaseous state, also known as free excited atoms, produce a line spectrum. Line spectra are produced by atomic substances such as sodium in a sodium vapor lamp, mercury in a mercury vapor lamp, and gases in a discharge tube.
What is band emission spectrum?
A spectrum made up of groups or bands of closely spaced lines. When the light emitted or absorbed by molecules is viewed through a spectroscope with a small dispersion, the spectrum appears to be made up of very wide asymmetrical lines known as bands. It is made up of a number of bright bands that have a sharp edge at one end but fade out at the other. Molecules are used to generate band spectra. It is a property of the molecule. Band spectra are produced by using calcium or barium salts in a bunsen flame and molecular gases such as carbon-di-oxide, ammonia, and nitrogen in the discharge tube. When the bands are examined with a high-resolution power spectrometer, it is discovered that each band is made up of a large number of fine lines that are very close to each other at the sharp edge but spaced out at the other end. The molecular structure of a substance can be studied using band spectra.
What is absorption spectra?
The spectrum obtained when light emitted from a source is made to pass through an absorbing material and then examined with a spectrometer is known as the absorption spectrum. It is a property of the absorbing substance. Similar to the types of emission spectrum, there are three types of absorption spectrum too.
- Continuous absorption spectrum
- Line absorption spectrum
- Band absorption spectrum
What is continuous absorption spectrum?
This is a spectrum that is never ending. When light passes through a gas, such as sunlight, the elements absorb some of the light, resulting in an absorption spectrum with absorption lines. When a gas is heated, the atoms absorb the energy and emit light, resulting in an emission spectrum. When a pure green glass plate is placed in the path of white light, it absorbs all colors except green and produces a continuous absorption spectrum.
What is line absorption spectrum?
An electromagnetic spectrum in which a decrease in the intensity of radiation at specific wavelengths of an absorbing substance is manifested, most notably as a pattern of dark lines or bands. When light from a carbon arc is passed through sodium vapor and then examined with a spectrometer, a continuous spectrum of carbon arc is obtained, with two dark lines in the yellow region.
What is band absorption spectrum?
Atoms and molecules, according to quantum mechanics, can only hold specific amounts of energy or exist in specific states. When such quanta of electromagnetic radiation are emitted or absorbed by an atom or molecule, the radiation’s energy changes the atom’s or molecule’s state from an initial to a final state. An absorption band is a range of wavelengths, frequencies, or energies in the electromagnetic spectrum that are associated with a specific transition from initial to final state in a substance. When white light is passed through iodine vapor, a dilute solution of blood or chlorophyll, or certain organic and inorganic compound solutions, dark bands on a continuous bright background result. The band absorption spectra are used in the production of dyes.
Emission spectrum vs absorption spectrum
Although both absorption and emission spectrum are the types of spectrum, but the emission lines are caused by glowing hot gas emitting lines of light, whereas absorption lines are caused by cool atmospheric gas absorbing the same lines of light. When light passes through atmospheric gas, some of the light at specific wavelengths is scattered, resulting in darker bands. These lines are known as spectral lines, and they were cataloged by heating common elements until they emit light. However, the main distinction between the emission spectrum and the absorption spectrum is that the absorption spectrum is continuous, whereas the emission spectrum is discontinuous or line. Let us now examine the primary difference between absorption spectrum and emission spectrum:
- Radiations emitted by excited atoms cause the emission spectra to be obtained. While, when atoms absorb energy, they produce absorption spectra.
- Emission spectrum is a discontinuous spectrum made up of a few wavelengths separated by a distinct gap. While absorption spectrum is a continuous spectrum with dark lines connecting all of the wavelengths.
- While displaying an emission spectrum, an atom will have more energy whereas, in absorption spectrum, an atom will have less energy.
These are some key distinctions between the absorption spectrum and the emission spectrum.