Forensic and Scientific

Vocabulary

This section of the Forensic Spectroscopy website has the definitions of some words that are used often when talking about forensics, spectroscopy, and science. The definitions are from BioTech's Life Science Dictionary, the On-line Medical Dictionary at CancerWEB, and Webster's Dictionary. Go to any of these sites to search for more terms; the BioTech site also has an acronym database for acronyms like FTIR (Fourier Transform Infrared Spectroscopy) that are used a lot to discuss materials or procedures in forensics or science. Click on any of the pictures for more information about a topic!

Absorption Spectroscopy: the use of a spectrophotometer to measure the ability of particles (solutes) in a solution to absorb light through a range of specific wavelengths. Every compound absorbs light differently, so absorption spectra can be used to identify compounds, measure concentrations, and determine reaction rates.

Acetone: a colorless, flammable liquid used as a solvent (for example, it is the solvent in nail polish remover). The simplest ketone, it mixes with water, ethyl alcohol, and most oils. Acetone is naturally found in very small amounts in body fluids and tissues of healthy people, and in somewhat larger amounts in people suffering from diabetes or starvation.

Alveoli: a small cell containing air in the lungs, a sac-like dilation of the alveolar ducts in the lung.

Analyte: the substance being measured in an analytical procedure.

Analytical Chemistry: the branch of chemistry that deals with the quantitative and qualitative identification of substances.

Chemistry: the scientific study of the composition, structure, properties, and interactions of chemicals. There are several branches of chemistry, including biochemistry, biogeochemistry, computational chemistry, cytochemistry, histochemistry, immunochemistry, and inorganic and organic chemistry.

Chromatography: a collection of techniques for separating molecules based on differential absorption and elution. Chromatography is the term for separation methods involving the flow of a fluid carrier over a nonmobile absorbing phase. The results of a chromatographic test are displayed as a chromatogram.

Clinical Chemistry: the use of laboratory chemistry techniques to aid in the diagnosis or treatment of diseases and disorders. Clinical chemistry techniques can involve such things as testing blood or urine for the presence of certain biomolecules or metabolites, therapeutic drug monitering, etc.

Concentration: the ratio of the mass or volume of a solute to the mass or volume of the solution or solvent. Or, the quantity of solute divided by the quantity of solvent.

Contamination: the introduction of unwanted microorganisms or chemicals in a laboratory culture.

Forensic Medicine: the use of medical techniques to help solve crimes. For instance, a clinical chemist might be called upon to determine the type or do DNA testing on blood found at a crime scene; a pathologist might examine and/or dissect a corpse to determine the time an cause of death; and a physician might examine a rape victim to verify his or her assault and to obtain semen or hair samples left by the attacker.

Gas Chromatography: a type of column chromatography in which the stationary phase is solid while the mobile phase is gaseous samples.

Infrared Light: electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves.

IR (infrared) Spectroscopy: a type of absorption spectroscopy which is used to measure the ability of an unknown sample to absorb different wavelengths of infrared radiation. How much infrared radiation is absorbed at each wavelength indicates the types of chemical bonds present in the molecules of the unknown sample.

Ketone: a byproduct of fat metabolism. An overabundance of ketones in the bloodstream is seen in a severe metabolic derangement known as diabetic ketoacidosis.

Polymer: a large molecule formed by the combination of many similar smaller molecules (monomers).

Radiation: propagation of energy through space.

Spectrophotometer: a machine used to measure how much light of a given wavelength is absorbed by a liquid sample, or to measure how intense (bright) the spectral lines and band produced by the sample are, relative to each other.

Spectroscopy: the science of measuring the emission and absorption of different wavelengths (spectra) of visible and non-visible light; this can be done via a spectroscope, which consists of a slit, prism, collimator lens, object lens, and a grating.

Wavelength: the length of a single cycle of a wave, usually measured from crest-to-crest. For electromagnetic waves, the wavelength determines the type (radio, infrared, visible, ultraviolet, X-ray, gamma-ray) or radiation; in the case of visible light, wavelength determines the color of the light.