Spéktroskopi
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Spéktroskopi ngarupakeun ulikan ngeunaan spéktra.
Spéktroskopi mindeng dipaké na kimia fisik sarta analitis pikeun idéntifikasi zat tina spéktrum nu mencar atawa nu diserepna. Parabot pikeun ngarékam spéktrum disebut spéktrométer. Spéktroskopi bisa digolongkeun dumasar kuantitas fisik nu diukur, diitung, atawa prosés ngukurna.
Spéktroskopi ogé kapaké pisan dina astronomi. Tempo spéktroskopi astronomis.
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[édit] Kuantitas fisik nu diukur
Tipe spéktroskopi gumantung kana kuantitas fisik nu rék diukur. Ilaharna, kuantitas nu diukur mangrupa jumlah atawa inténsitas.
- Inténsitas radiasi éléktromagnetik nu dipencarkeun jeung jumlah nu diserep diulik ku spéktroskopi éléktromagnetik.
- Amplitudo geteran/vibrasi makroskopik diulik ku spéktroskopi akustik jeung spéktroskopi mékanis dinamik.
- Énergi kinetik partikel diulik ku electron energy loss spectroscopy, spéktroskopi éléktron Auger
- Nisbah massa ka muatan molekul jeung atom diulik dina spéktrométri massa. Catet yén spéktrométer massa teu ngukur énergi kinetik partikel: sadaya partikel mibanda énergi kinetik nu sarua sarta geus kanyahoan (or an integer multiple thereof, depending on the charge). It is disputable whether this field strictly is a type of spectroscopy.
- Jumlah molekul atawa atom atawa kuantum-mékanik nangtukeun kamana paraméter frékuénsi atawa énergi dilarapkeun.
[édit] Prosés ngukur
Tipe spéktroskopi nu béda dipaké dina prosés ngukur nu béda:
[édit] Dua tipe utama spéktroskopi
Spéktroskopi Absorpsi uses the range of electromagnetic spectra in which a substance absorbs. It is more commonly used. The sample is vaporised and then light of a particular frequency is passed through the vapour. After calibration, the amount of absorption can be related to the concentrations of various metal ions. The method can be automated and is widely used to measure concentrations of ions such as sodium and calcium in blood. ( Atomic Absorption Spectroscopy )
Spéktroskopi Émisi uses the range of electromagnetic spectra in which a substance radiates. It requires the substance to be vaporised at high temperatures by placing it in a spark gap.
[édit] Tipe spéktroskopi nu ilahar
X-ray spectroscopy and X-ray crystallography When X-rays of sufficient frequency (energy) interact with a substance, inner shell electrons in the atom are excited to outer empty orbitals, or they may be removed completely, ionizing the atom. The inner shell "hole" will then be filled by electrons from outer orbitals. The energy available in this de-excitation process is emitted as radiation (fluorescence) or will remove other less-bound electrons from the atom (Auger effect). The absorption or emission frequencies (energies) are characteristic of the specific atom. In addition, for a specific atom small frequency (energy) variations occur which are characteristic of the chemical bonding. With a suitable apparatus, these characteristic X-ray frequencies or Auger electron energies can be measured. X-ray absorption and emission spectroscopy is e.g. used in chemistry and material sciences to determine elemental composition and chemical bonding.
X-ray crystallography is a process in which X-rays are shone onto crystals at a certain angle. The wavelength of the X-rays is known and so the distance apart of the crystal planes can be calculated. Combining all information enables crystal structure to be detected.
Visible spectroscopy
Many atoms emit or absorb visible light. In order to obtain a fine line spectrum, the atoms must be in a gas phase. This means that the substance has to be vaporised. Spectrum is studied in absorption or emission.
UV spectroscopy
All atoms absorb in the UV region because photons are energetic enough to excite outer electrons. If the frequency is high enough, Photoionisation takes place.
Photoemission spectroscopy
[édit] Less frequently used / combined spectroscopy
- Fourier transform is an efficient method for collecting various spectra. The use of Fourier transform in spectroscopy is called Fourier transform spectroscopy. It is frequently applied to infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy.
- Spectroscopy of matter in situations where the properties are changing with time is called Time-resolved spectroscopy.
- Spectroscopy using an AFM-based analytical technique is called Force spectroscopy.
- Dielectric spectroscopy
