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Molekulaspektroszkopia segédábrák
Az ábrák több, részben szerzői jogokkal védett műből, oktatási célra lettek kivéve. Csak az intranetre tehetők, továbbmásolásuk,
terjesztésük nem megengedett.
Az ábrák csak illusztrációs célokat szolgálnak. Mivel többnyire más szerzők műveiből származnak, olyan jelölések vagy állítások is
előfordulhatnak bennük, amelyekkel a tantárgy oktatói nem teljesen értenek egyet.
"Heat“
Infrared radiation is popularly known as "heat" or sometimes "heat radiation," since many people
attribute all radiant heating to infrared light, but this is a widespread misconception. Light and
electromagnetic waves of any frequency will heat surfaces which absorb them. IR light from the sun
only accounts for 50% of the heating of the Earth, the rest being caused by visible light. Green (or even UV) lasers can char paper and incandescently hot objects
put out visible radiation. However, it is true that objects at room temperature will emit radiation mostly
concentrated in the 8-12 micron band (see black body).
Die Wellenlänge der Ultraviolettstrahlung reicht von 1 nm bis 380 nm.
Die Frequenz der Ultraviolettstrahlung reicht also von 789 THz (380 nm) bis 300 PHz (1 nm).
Die Energie eines einzelnen Lichtquants liegt im Bereich von ca. 3,3 eV (380 nm) bis ca. 1000 eV (1 nm). 1 eV = 1,602 176 462(63) · 10-19 JEin typisches Molekül in der Atmosphäre hat eine Bewegungsenergie (thermische Energie) von etwa 0,03 eV. Die Photonen von sichtbarem Licht (rot) haben eine Energie von etwa 2 eV.
Boltzman-Konstante 1,38 · 10-23 J K-1 8,62· 10-5 eV K-1
Plancksches Wirkungsquantum h 4,14 · 10-15 eV s
Die ultraviolette Strahlung wurde 1802 von Johann Wilhelm Ritter entdeckt.
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. It can be subdivided into near UV (380–200 nm wavelength; abbrev. NUV), far or vacuum UV (200–10 nm; abbrev. FUV or VUV), and extreme UV (1–31 nm; abbrev. EUV or XUV).
When considering the effect of UV radiation on human health and the environment, the range of UV wavelengths is often subdivided into UVA (400–315 nm), also called Long Wave or "blacklight"; UVB (315–280 nm), also called Medium Wave; and UVC (< 280 nm), also called Short Wave or "germicidal".
Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while
Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350
nm, but blocks over 90% of the light below 300 nm[1][2][3].
The onset of vacuum UV, 200 nm, is defined by the fact that ordinary air is opaque below this wavelength. This opacity is due to the strong absorption of light of these
wavelengths by oxygen in the air. Pure nitrogen (less than about 10 ppm oxygen) is transparent to wavelengths in the range of about 150–200 nm. This has wide practical
significance now that semiconductor manufacturing processes are using wavelengths shorter than 200 nm.
Copyrighted, 1998 - 2006 by Nick Strobel www.astronomynotes.com.
Copyrighted, 1998 - 2006 by Nick Strobel www.astronomynotes.com
Properties of Electromagnetic RadiationFig. 19-1, pg. 511 ”Plane-polarized electromagnetic radiation of wavelength , propagating along the x axis. The electric field of the plane-polarized light is confined to a single plane. Ordinary, unpolarized light has electric field components in all planes."
Regions ofElectromagnetic Spectrum
Attenuation of Light
Grating vs. Prism
Beer's LawInstrumental response
G = KP + K'
100% adjust, incident radiation
Go = 100 = KPo + 0.00
K = 100/Po
Spectronic 20
Double Beam Spectrometer
HP 8452a
Components of Optical Instruments
Fig. 7-2, pg. 145 ”(a) Construction materials
Components of Optical Instruments
Fig. 7-2, pg. 145 ”(b) wavelength selectors for spectroscopic instruments."
Components of Optical Instruments
Fig. 7-3, pg. 146 ”(a) Sources."
Components of Optical Instruments
Fig. 7-3, pg. 146 ”(b) detectors for spectroscopic instruments."
Properties ofElectromagnetic Radiation
Fig. 6-2, pg. 118 "Effect of change of medium on a monochromatic beam of radiation."
Properties ofElectromagnetic RadiationFig. 6-3, pg. 119 "Regions of the electromagnetic spectrum"
Absorption of Radiation
Fig. 6-19, pg.134 "Some typical ultraviolet absorption spectra."
Monochromator Slits
Construction of slits
Total Absorption
AT = A1 + A2 + A3 + An
AT = 1bc1 + 2bc2 + bc3 + nbcn
Analysis of Mixtures of Absorbing Substances
Selection of Wavelength
Fig. 14-14, pg. 345 "Absorption spectrum of a two-component mixture."
Real Deviations
non-monochromatic radiationFig. 13-4, pg. 305"Deviations Beer's Law with polychromatic light. Here, two wavelenghts or radiation 1 and 2 have been assumed for which the absorber has the indicated molar absorptivities."
Real Deviations
Fig. 13-5, pg. 306"The effect of polychromatic radiation upon the Beer's law relationship. Band A shows little deviation, because does not change greatly throughout the band. Band B shows marked deviations because undergoes significant changes in this region."
Real Deviations
stray light
Fig. 13-6, pg. 307
"Apparent deviation from Beer's law brought about by various amounts of stray radiation."
Single Beam vs. Double BeamFig. 13-12, pg. 315
"Instrument designs for photometers and spectrophotometers:
(a) single-beam design
(b) dual channel design with beams separated in space but simultaneous in time
(c) double-beam design in which beams alternate between two channels."
Types of TransitionsFig. 14-1, pg. 331 "Electron distribution in sigma and pi molecular orbitals."
Types of TransitionsFig. 14-2, pg. 331 "Types of molecular orbitals in formaldehyde."
Absorbing Species Containing , , and n
ElectronsFig. 14-3, pg. 331
"Electonic molecular energy levels."
n
Antibonding
Antibonding
Nonbonding
Bonding
Bonding
n
n
UV Spectra
Fig. 14-4, pg. 334 “Ultraviolet spectra for typical organic compounds.”
Visible Spectra
Fig. 14-5, pg 334 “Ultraviolet absorption spectra for 1,2,4,5-tetrazine (a.) in the vapor phase, (b.) in hexane solution, and (c.) in aqueous solution.”
Types of Transitions
Table 14-2, pg. 333 "Aborption Characteristics of Some Common Chromophores."
Types of TransitionsTable 14-3, pg. 355 "Effect of Multichromophores on Absorption."
Interferogram vs. Spectrum
Qualitative Analysis
Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.
Qualitative Analysis
Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.
Qualitative Analysis
Fig. 17-4, pg. 408 Group frequency and fingerprint regions of the mid-infrared spectrum.
Vibration Modes
Fig. 16-2, pg. 383 “Types of molecular vibrations. Note: + indicates motion from the page toward the reader; - indicates motion away from the reader.”
Potential Energy DiagramFig. 16-3, pg. 384 “Potential energy diagrams. Curve 1, harmonic oscillator. Curve 2, anharmonic oscillator.”
Infrared Sources
Most Common IR Sources
• Nernst glower– cylinder of rare-earth oxides
• glowbar– silicon carbide rod– 50mm long by 5mm diameter
• incandescent wire– nichrome wire
Infrared Detectors
• thermocouples
• pyroelectrics
Table 17-1, pg. 405Major Applications of Infrared Spectrometry
SpectralRegions
Type ofMeasurement
Type ofAnalysis
TypeSamples
Near-infrared Diffusereflectance
Quantitative Solid or liquidmaterials ofcommerce
Absorption Quantitative Gaseousmixtures
Table 17-1, pg. 405Major Applications of Infrared Spectrometry
SpectralRegions
Type ofMeasurement
Type ofAnalysis
TypeSamples
Mid-infrared Absorption Qualitative Pure solid,liquid, orgaseouscompounds
Quantitative Complexgaseous,liquid or solidmixtures
Chromatographic Complexgaseous,liquid, or solidmixtures
Table 17-1, pg. 405Major Applications of Infrared Spectrometry
SpectralRegions
Type ofMeasurement
Type ofAnalysis
TypeSamples
Mid-infrared Reflectance Qualitative Pure solidor liquidcompounds
Emission Quantitative Atmosphericsamples
Table 17-1, pg. 405Major Applications of Infrared Spectrometry
SpectralRegions
Type ofMeasurement
Type ofAnalysis
TypeSamples
Far-infrared Absorption Qualitative Pure inorgancior metalorganicspecies
Sample Techniques
film
smear
sample cell
gas cell
KBr pellet
Nujol mull
internal reflectance apparatus
Deuterium lamps are gas discharge lamps filled with Deuterium at carefully controlled pressures. They provide a line free continuous UV spectrum from 180nm to 370nm,
Tungsten Halogen lamps (TH) are compact gas filled filament lamps that provide a continuum output from 350nm to 1000nm.
Emission spectrum of an ultraviolet deuterium arc lamp
