Classification of methods Spectroscopy

1 classification of methods

1.1 type of radiative energy
1.2 nature of interaction
1.3 type of material

1.3.1 atoms
1.3.2 molecules
1.3.3 crystals , extended materials
1.3.4 nuclei

classification of methods

a huge diffraction grating @ heart of ultra-precise espresso spectrograph.

spectroscopy sufficiently broad field many sub-disciplines exist, each numerous implementations of specific spectroscopic techniques. various implementations , techniques can classified in several ways.

type of radiative energy

types of spectroscopy distinguished type of radiative energy involved in interaction. in many applications, spectrum determined measuring changes in intensity or frequency of energy. types of radiative energy studied include:

electromagnetic radiation first source of energy used spectroscopic studies. techniques employ electromagnetic radiation typically classified wavelength region of spectrum , include microwave, terahertz, infrared, near infrared, visible , ultraviolet, x-ray , gamma spectroscopy.
particles, due de broglie wavelength, can source of radiative energy , both electrons , neutrons commonly used. particle, kinetic energy determines wavelength.
acoustic spectroscopy involves radiated pressure waves.
mechanical methods can employed impart radiating energy, similar acoustic waves, solid materials.

nature of interaction

types of spectroscopy can distinguished nature of interaction between energy , material. these interactions include:

absorption occurs when energy radiative source absorbed material. absorption determined measuring fraction of energy transmitted through material; absorption decrease transmitted portion.
emission indicates radiative energy released material. material s blackbody spectrum spontaneous emission spectrum determined temperature; feature can measured in infrared instruments such atmospheric emitted radiance interferometer (aeri). emission can induced other sources of energy such flames or sparks or electromagnetic radiation in case of fluorescence.
elastic scattering , reflection spectroscopy determine how incident radiation reflected or scattered material. crystallography employs scattering of high energy radiation, such x-rays , electrons, examine arrangement of atoms in proteins , solid crystals.
impedance spectroscopy studies ability of medium impede or slow transmittance of energy. optical applications, characterized index of refraction.
inelastic scattering phenomena involve exchange of energy between radiation , matter shifts wavelength of scattered radiation. these include raman , compton scattering.
coherent or resonance spectroscopy techniques radiative energy couples 2 quantum states of material in coherent interaction sustained radiating field. coherence can disrupted other interactions, such particle collisions , energy transfer, , require high intensity radiation sustained. nuclear magnetic resonance (nmr) spectroscopy used resonance method , ultrafast laser methods possible in infrared , visible spectral regions.

type of material

spectroscopic studies designed radiant energy interacts specific types of matter.

atoms

atomic spectroscopy first application of spectroscopy developed. atomic absorption spectroscopy (aas) , atomic emission spectroscopy (aes) involve visible , ultraviolet light. these absorptions , emissions, referred atomic spectral lines, due electronic transitions of outer shell electrons rise , fall 1 electron orbit another. atoms have distinct x-ray spectra attributable excitation of inner shell electrons excited states.

atoms of different elements have distinct spectra , therefore atomic spectroscopy allows identification , quantitation of sample s elemental composition. robert bunsen , gustav kirchhoff discovered new elements observing emission spectra. atomic absorption lines observed in solar spectrum , referred fraunhofer lines after discoverer. comprehensive explanation of hydrogen spectrum success of quantum mechanics , explained lamb shift observed in hydrogen spectrum, further led development of quantum electrodynamics.

modern implementations of atomic spectroscopy studying visible , ultraviolet transitions include flame emission spectroscopy, inductively coupled plasma atomic emission spectroscopy, glow discharge spectroscopy, microwave induced plasma spectroscopy, , spark or arc emission spectroscopy. techniques studying x-ray spectra include x-ray spectroscopy , x-ray fluorescence (xrf).

molecules

the combination of atoms molecules leads creation of unique types of energetic states , therefore unique spectra of transitions between these states. molecular spectra can obtained due electron spin states (electron paramagnetic resonance), molecular rotations, molecular vibration , electronic states. rotations collective motions of atomic nuclei , typically lead spectra in microwave , millimeter-wave spectral regions; rotational spectroscopy , microwave spectroscopy synonymous. vibrations relative motions of atomic nuclei , studied both infrared , raman spectroscopy. electronic excitations studied using visible , ultraviolet spectroscopy fluorescence spectroscopy.

studies in molecular spectroscopy led development of first maser , contributed subsequent development of laser.

crystals , extended materials

the combination of atoms or molecules crystals or other extended forms leads creation of additional energetic states. these states numerous , therefore have high density of states. high density makes spectra weaker , less distinct, i.e., broader. instance, blackbody radiation due thermal motions of atoms , molecules within material. acoustic , mechanical responses due collective motions well. pure crystals, though, can have distinct spectral transitions, , crystal arrangement has effect on observed molecular spectra. regular lattice structure of crystals scatters x-rays, electrons or neutrons allowing crystallographic studies.

nuclei

nuclei have distinct energy states separated , lead gamma ray spectra. distinct nuclear spin states can have energy separated magnetic field, , allows nmr spectroscopy.