Presentation "Optical devices. Spectral devices." Presentation on the topic "spectral devices." Dependence of angular dispersion on the refractive angle
These are spectra containing all wavelengths of a certain range. These are spectra containing all wavelengths of a certain range. They emit heated solid and liquid substances, gases heated under high pressure. They are the same for different substances, so they cannot be used to determine the composition of a substance
Consists of individual lines of different or the same color, having different locations Consists of individual lines of different or the same color, having different locations Emitted by gases, low-density vapors in the atomic state Allows one to judge the chemical composition of the light source from spectral lines
This is a set of frequencies absorbed by a given substance. A substance absorbs those lines of the spectrum that it emits, being a source of light. This is a set of frequencies absorbed by a given substance. A substance absorbs those lines of the spectrum that it emits, being a source of light. Absorption spectra are obtained by passing light from a source that produces a continuous spectrum through a substance whose atoms are in an unexcited state
Pointing a very large telescope at a brief meteor flash in the sky is almost impossible. But on May 12, 2002, astronomers were lucky - a bright meteor accidentally flew right where the narrow slit of the spectrograph at the Paranal Observatory was aimed. At this time, the spectrograph examined the light. Pointing a very large telescope at a brief meteor flash in the sky is almost impossible. But on May 12, 2002, astronomers were lucky - a bright meteor accidentally flew right where the narrow slit of the spectrograph at the Paranal Observatory was aimed. At this time, the spectrograph examined the light.
The method of determining the qualitative and quantitative composition of a substance from its spectrum is called spectral analysis. Spectral analysis is widely used in mineral exploration to determine the chemical composition of ore samples. It is used to control the composition of alloys in the metallurgical industry. On its basis, the chemical composition of stars, etc., was determined. The method of determining the qualitative and quantitative composition of a substance from its spectrum is called spectral analysis. Spectral analysis is widely used in mineral exploration to determine the chemical composition of ore samples. It is used to control the composition of alloys in the metallurgical industry. On its basis, the chemical composition of stars, etc., was determined.
To obtain the spectrum of visible radiation, a device called a spectroscope is used, in which the human eye serves as a radiation detector. To obtain the spectrum of visible radiation, a device called a spectroscope is used, in which the human eye serves as a radiation detector.
In a spectroscope, light from the source 1 under study is directed to the slit 2 of the tube 3, called the collimator tube. The slit emits a narrow beam of light. At the second end of the collimator tube there is a lens that converts the diverging beam of light into a parallel one. A parallel beam of light emerging from the collimator tube falls on the edge of glass prism 4. Since the refractive index of light in glass depends on the wavelength, therefore, a parallel beam of light, consisting of waves of different lengths, decomposes into parallel beams of light of different colors, traveling along different directions. The telescope lens 5 focuses each of the parallel beams and produces an image of the slit in each color. Multi-colored images of the slit form a multi-colored stripe - a spectrum. In a spectroscope, light from the source 1 under study is directed to the slit 2 of the tube 3, called the collimator tube. The slit emits a narrow beam of light. At the second end of the collimator tube there is a lens that converts the diverging beam of light into a parallel one. A parallel beam of light emerging from the collimator tube falls on the edge of glass prism 4. Since the refractive index of light in glass depends on the wavelength, therefore, a parallel beam of light, consisting of waves of different lengths, decomposes into parallel beams of light of different colors, traveling along different directions. The telescope lens 5 focuses each of the parallel beams and produces an image of the slit in each color. Multi-colored images of the slit form a multi-colored stripe - a spectrum.
The spectrum can be observed through an eyepiece used as a magnifying glass. If you need to take a photograph of a spectrum, then photographic film or a photographic plate is placed in the place where the actual image of the spectrum is obtained. A device for photographing spectra is called a spectrograph.
The researcher, using an optical spectroscope, saw different spectra in four observations. Which spectrum is the thermal radiation spectrum? The researcher, using an optical spectroscope, saw different spectra in four observations. Which spectrum is the thermal radiation spectrum?
What bodies are characterized by striped absorption and emission spectra? What bodies are characterized by striped absorption and emission spectra? For heated solids For heated liquids For rarefied molecular gases For heated atomic gases For any of the above bodies
Which bodies are characterized by line absorption and emission spectra? Which bodies are characterized by line absorption and emission spectra? For heated solids For heated liquids For rarefied molecular gases For heated atomic gases For any of the above bodies
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Spectra. spectral analysis. Spectral devices Radiation sources Types of spectra
Emission spectra
- solid
- ruled
- striped
Absorption spectra
Continuous spectrum
- These are spectra containing all wavelengths of a certain range.
- They emit heated solid and liquid substances, gases heated under high pressure.
- They are the same for different substances, so they cannot be used to determine the composition of a substance
- Consists of individual lines of different or the same color, having different locations
- Emitted by gases and low-density vapors in the atomic state
- Allows you to judge the chemical composition of the light source by spectral lines
- Consists of a large number of closely spaced lines
- Give substances that are in a molecular state
- This is a set of frequencies absorbed by a given substance. The substance absorbs those lines of the spectrum that it emits, being a source of light
- Absorption spectra are obtained by passing light from a source producing a continuous spectrum through a substance whose atoms are in an unexcited state
- The method of determining the qualitative and quantitative composition of a substance from its spectrum is called spectral analysis. Spectral analysis is widely used in mineral exploration to determine the chemical composition of ore samples. It is used to control the composition of alloys in the metallurgical industry. On its basis, the chemical composition of stars, etc., was determined.
- To obtain the spectrum of radiation in the visible range, a device called spectroscope, in which the human eye serves as a radiation detector.
2. Select one correct answer from the given options only nitrogen (N) and potassium (K) only magnesium (Mg) and nitrogen (N) nitrogen (N), magnesium (Mg) and another unknown substance magnesium (Mg), potassium (K ) and nitrogen (N)
The figure shows the absorption spectrum of an unknown gas and the absorption spectra of vapors of known metals. Based on the analysis of the spectra, it can be stated that the unknown gas contains atoms
3. Select one correct answer from the given options. Which bodies are characterized by striped absorption and emission spectra? For heated solids For heated liquids For rarefied molecular gases For heated atomic gases For any of the above bodies
4. Select one correct answer from the proposed options. Which bodies are characterized by line absorption and emission spectra? For heated solids For heated liquids For rarefied molecular gases For heated atomic gases For any of the above bodies
5. Choose one correct answer from the given options. Radiation from which body is thermal? Fluorescent lamp Incandescent lamp Infrared laser TV screen
Continuous spectra are produced by bodies in solid and liquid states, as well as highly compressed gases. Line spectra give all substances in the gaseous atomic state. Isolated atoms emit strictly defined wavelengths. Striped spectra, in contrast to line spectra, are created not by atoms, but by molecules that are not bound or weakly bound to each other.
They produce bodies in solid and liquid states, as well as dense gases. To obtain it, you need to heat the body to a high temperature. The nature of the spectrum depends not only on the properties of individual emitting atoms, but also on the interaction of atoms with each other. The spectrum contains waves of all lengths and there are no breaks. A continuous spectrum of colors can be observed on a diffraction grating. A good demonstration of the spectrum is the natural phenomenon of a rainbow. Uchim.net
All substances are produced in a gaseous atomic (but not molecular) state (the atoms practically do not interact with each other). Isolated atoms of a given chemical element emit waves of a strictly defined length. For observation, the glow of vapor of a substance in a flame or the glow of a gas discharge in a tube filled with the gas under study is used. As the density of the atomic gas increases, individual spectral lines broaden. Uchim.net
The spectrum consists of individual bands separated by dark spaces. Each stripe is a collection of a large number of very closely spaced lines. They are created by molecules that are not bound or weakly bound to each other. For observation, the glow of vapors in a flame or the glow of a gas discharge is used. Uchim.net
Gustav Robert Kirchhoff Robert Wilhelm Bunsen Uchim.net Spectral analysis is a method of determining the chemical composition of a substance from its spectrum. Developed in 1859 by German scientists G. R. Kirchhoff and R. W. Bunsen.
If white light is passed through a cold, non-emitting gas, dark lines will appear against the continuous spectrum of the source. Gas absorbs most intensely the light of those wavelengths that it emits in a highly heated state. Dark lines against the background of a continuous spectrum are absorption lines that together form the absorption spectrum. Uchim.net
New elements are discovered: rubidium, cesium, etc.; We learned the chemical composition of the Sun and stars; Determine the chemical composition of ores and minerals; Method for monitoring the composition of a substance in metallurgy, mechanical engineering, and the nuclear industry. The composition of complex mixtures is analyzed by their molecular spectra. Uchim.net
Spectra of stars are their passports with a description of all stellar features. Stars are composed of the same chemical elements that are known on Earth, but in percentage terms they are dominated by light elements: hydrogen and helium. From the spectrum of a star, you can find out its luminosity, distance to the star, temperature, size, chemical composition of its atmosphere, speed of rotation around its axis, features of movement around the common center of gravity. A spectral apparatus mounted on a telescope separates star light by wavelength into a spectrum strip. From the spectrum, you can find out what energy comes from the star at different wavelengths and estimate its temperature very accurately.
Stationary spark optical emission spectrometers “METALSKAN –2500”. Designed for precise analysis of metals and alloys, including non-ferrous, ferrous alloys and cast irons. Laboratory electrolysis installation for metal analysis "ELAM". The installation is intended for carrying out gravimetric electrolytic analysis of copper, lead, cobalt and other metals in alloys and pure metals. Currently, television spectral systems (TSS) are widely used in forensic science. - detection of various types of document forgeries: - detection of filled-in, crossed out or faded (faded) texts, records formed by pressed strokes or made on carbon paper, etc.; - identification of tissue structure; - detection of contaminants on fabrics (soot and mineral oil residues) in case of gunshot injuries and transport accidents; - identification of washed-out, as well as traces of blood located on motley, dark and contaminated objects.
Slide 2
Classification of spectral devices.
Slide 3
Spectral devices are devices in which light is decomposed into wavelengths and the spectrum is recorded. There are many different spectral instruments that differ from each other in their recording methods and analytical capabilities.
Slide 4
Having chosen a light source, care must be taken to ensure that the resulting radiation is effectively used for analysis. This is achieved by choosing the right spectral device
Slide 5
There are filter and dispersive spectral devices. In filters, a light filter selects a narrow range of wavelengths. In dispersive ones, the source radiation is decomposed into wavelengths in a dispersive element - a prism or diffraction grating. Filter devices are used only for quantitative analysis, dispersion devices are used for qualitative and quantitative
Slide 6
There are visual, photographic and photoelectric spectral instruments. Steeloscopes are instruments with visual registration, Spectrographs are instruments with photographic registration. Spectrometers are instruments with photoelectric recording. Filter devices - with photoelectric registration. In spectrometers, decomposition into a spectrum is done in a monochromator or in a polychromator. Devices based on a monochromator are called single-channel spectrometers. Devices based on a polychromator - multichannel spectrometers.
Slide 7
All dispersion devices are based on the same circuit diagram. Devices may differ in their registration method and optical characteristics, they may have different appearance and design, but the principle of their operation is always the same. Schematic diagram of a spectral device. S - entrance slit, L 1 - collimator lens, L 2 - focusing lens, D - dispersing element, R - recording device.
Slide 8
S L 1 D L 2 R Light from the source enters the spectral device through a narrow slit and from each point of this slit in the form of divergent beams it hits the collimator lens, which converts the divergent beams into parallel ones. The slit and the collimator lens make up the collimator part of the device. Parallel beams from the collimator lens fall on a dispersing element - a prism or diffraction grating, where they are decomposed into wavelengths. From the dispersing element, light of the same wavelength, coming from one point of the slit, emerges in a parallel beam and hits a focusing lens, which collects each parallel beam at a certain point on its focal surface - on the recording device. Numerous monochromatic images of the slit are formed from individual points. If individual atoms emit light, a series of individual images of the slit are obtained in the form of narrow lines - a line spectrum. The number of lines depends on the complexity of the spectrum of the emitting elements and the conditions of their excitation. If individual molecules glow in a source, then lines that are close in wavelength are collected into bands, forming a striped spectrum. Operating principle of a spectral device.
Slide 9
purpose of the slot
R S Entrance slit – image object Spectral line – monochromatic image of the slit, constructed using lenses.
Slide 10
lenses
L 2 L 1 lenses spherical mirrors
Slide 11
Collimator lens
S F O L1 The slit is located in the focal surface of the collimator lens. After the collimator lens, light comes from each point of the slit in a parallel beam.
Slide 12
Focusing lens
Spectral line F O L2 Constructs an image of each slit point. Formed from dots. slit image – spectral line.
Slide 13
dispersing element
D Dispersing prism diffraction grating
Slide 14
Dispersing prism ABCD is the base of the prism, ABEF and FECD are the refractive edges, Between the refracting faces is the refractive angle EF - the refractive edge.
Slide 15
Types of dispersing prisms
60 degree prism Quartz Cornu prism; 30-degree prism with mirror edge;
Slide 16
rotating prisms
Rotating prisms play a supporting role. They do not decompose radiation into wavelengths, but only rotate it, making the device more compact. Rotate 900 Rotate 1800
Slide 17
combined prism
The constant deflection prism consists of two thirty-degree dispersing prisms and one rotating one.
Slide 18
Path of a monochromatic beam in a prism
i In a prism, a ray of light is refracted twice at the refractive faces and leaves it, deviating from the original direction by an angle of deflection . The angle of deflection depends on the angle of incidence and the wavelength of the light. At a certain i, light passes through the prism parallel to the base, and the angle of deflection is minimal. In this case, the prism operates under conditions of minimal deflection.
Slide 19
Path of rays in a prism
2 1 1 2 Light decomposition occurs due to the fact that light of different wavelengths is refracted differently in a prism. Each wavelength has its own deflection angle.
Slide 20
Angular dispersion
1 2 Angular dispersion B is a measure of the efficiency of light decomposition into wavelengths in a prism. Angular dispersion shows how much the angle between two nearby rays changes with changing wavelength:
Slide 21
Dependence of dispersion on prism material quartz glass
Slide 22
Dependence of angular dispersion on the refractive angle
glass glass
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