Atom and Valence Electron Signals X-Rays Gamma-Rays

ATOM AND VALENCE ELECTRON SIGNALS – X-RAYS – GAMMA-RAYS

Radiation E range What can it do γ-rays 0.1 to 0.0001 nm Can promote or remove inner (core) electrons x-rays 50 to 0.1 nm Can promote or remove inner (core) electrons Can break molecular bonds. Results in the removal Vacuum UV 10-190 nm or promotion of electrons to excited states Can break molecular bonds. Results in the removal UV 190-300 nm or promotion of electrons to excited states Results in the removal or promotion of electrons to Visible 350 to 800 nm excited states IR 0.8-300 μm Increases the amplitude of vibrations Microwaves ~1-4 mm Increases the rate of molecular rotation

1 IG WHAT ATOM CAN SAY TO US?

Infrared Infrared Spectroscopy is the The main use of this technique (outer electrons and/or analysis of infrared light is in organic and inorganic valence electrons) interacting with a molecule. chemistry. It is used by This can be analyzed in three chemists to determine ways by measuring absorption, functional groups in molecules. emission and reflection. IR Spectroscopy measures the vibrations of atoms, and based on this it is possible to determine the functional groups. Generally, stronger bonds and light atoms will vibrate at a high stretching frequency (wave number). UV-Vis-NIR UV/Vis spectroscopy is Refers to absorption (outer electrons and/or routinely used in analytical spectroscopy or reflectance valence electrons) chemistry for the quantitative spectroscopy in the ultraviolet- determination of different visible spectral region. This analytes, such as transition means it uses light in the metal ions, highly conjugated visible and adjacent (near-UV organic compounds, and and near-infrared [NIR]) biological macromolecules. ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, molecules undergo electronic transitions. This technique is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state.

3 IG X rays The most abundant is X-ray When an electron from the (inner electrons) emission spectroscopy. It is inner shell of an atom is excited routinely used for qualitative by the energy of a photon, it and quantitative analysis of moves to a higher energy level, inorganic materials. There are which is shown as an outer two types of X-ray emission shell; the difference in energy spectroscopy: is emitted as a photon which  Energy-dispersive X-ray has a wavelength that is spectroscopy (EDS), and characteristic for the element  Wavelength dispersive X- (there could be several of ray spectroscopy (WDS). characteristic wavelengths per element). Analysis of the X-ray emission spectrum produces qualitative results about elemental composition of the specimen. Comparison of spectrum of the specimen with spectra of standards of known composition produces quantitative results (after some mathematical corrections for absorption, fluorescence and atomic number). Gamma rays Gamma spectroscopy is Most radioactive sources (from atom nucleus) the science of identification produce gamma rays, which are and/or quantification of of various energies and radionuclides by analysis of intensities. When these the gamma-ray energy emissions are detected and spectrum produced in a analyzed with a spectroscopy gamma-ray spectrometer. system, a gamma-ray energy It is a widely used technique. spectrum can be produced. A detailed analysis of this spectrum is typically used to determine the identity and quantity of gamma emitters present in a gamma source, and is a vital tool in radiometric assay. The gamma spectrum is characteristic of the gamma- emitting nuclides contained in the source, just as in optical spectroscopy, the optical spectrum is characteristic of the material contained in a sample. Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources, in such as the nuclear industry, geochemical investigation, and astrophysics.

5 IG Spectroscopy

 FT-IR  Raman Infrared  Rotational  Vibrational

 Ultraviolet-visible  Fluorescence UV-Vis-NIR  Vibronic  Near-infrared  Laser-induced

 Photoelectron X-ray and  Atomic Photoelectron  Emission

 Gamma Nucleon  Mössbauer

 NMR  Terahertz Radio wave  ESR/EPR  Ferromagnetic resonance