Introduction
Radioactivity and Radionuclides
- Radioactivity: Defined as the spontaneous emission of particles or radiation from unstable atomic nuclei.
- Radionuclides: These are atoms with unstable nuclei that undergo radioactive decay, emitting particles like alpha and beta, or radiation such as gamma rays to achieve stability.
Alpha and Beta Nuclear Transformations, Energy Spectra
- Alpha Decay: This decay involves the emission of an alpha particle from a nucleus, resulting in a new element with reduced atomic mass by four units and atomic number by two units.
- Beta Decay: There are two forms:
- Beta-minus (β-) decay: A neutron transforms into a proton, an electron, and an anti-neutrino.
- Beta-plus (β+) decay: A proton is converted into a neutron, a positron, and a neutrino.
- Energy Spectra: The energy spectrum of beta decay is continuous, whereas alpha decay exhibits a more discrete spectrum.
Gamma Radiation Spectra
- Gamma Radiation: This is electromagnetic radiation emitted either during radioactive decay or from interactions involving subatomic particles.
- Gamma Spectra: Characterized by discrete energy levels reflecting the energy states transitions of a nucleus.
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Metastable State, Isometric Transition
- Metastable State: A nucleus can exist in this high-energy state longer than usual due to factors like angular momentum, delaying its decay.
- Isometric Transition: This process involves the transition of a nucleus from a metastable state to a lower energy state, typically accompanied by the emission of gamma radiation.
Transitions in Molecules
- Types of Molecular Transitions:
- Electronic transitions: Changes in electronic configurations of molecules.
- Vibrational transitions: Adjustments in the vibrational motion of atoms within a molecule.
- Rotational transitions: Alterations in the rotational motion of the molecule.
Molecular Spectral Analysis, Types of Spectrophotometry
- Molecular Energy Levels: Total energy is expressed as E = Ee + Ev + Er, where Ee, Ev, and Er represent electronic, vibrational, and rotational energies, respectively.
- Molecular Spectral Analyzers:
- Structural Analysis: Identifies specific atomic groups or chemical bonds.
- Qualitative Analysis: Determines the types of chemical substances.
- Quantitative Analysis: Measures substance concentrations.
- Types of Equipment:
- Spectrometers: Analyze light properties over a spectrum for composition analysis.
- Photocolorimeters: Measure color intensity in solutions by light absorbance.
- Spectrophotometers: Determine analyte concentrations in solutions through light absorption at various wavelengths.