Spectroscopy

Electromagnetic Radiation Light travels in waves Highest point in wave = crest Distance b/t 2 crests = wavelength Frequency = how many waves pass a specific point w/in a given time ex. High freq = short wavelength

Types: visible light, X rays, radiowaves, microwaves Used for: - latent fingerprints - trace evidence on clothes - structure of a molecule

Spectroscopy Used to: - ID fibers & trace evidence - detect contaminants, accelerants, explosive residue Measures wavelength of light emitted & captures image (lines) on photographic film

Each element produces a unique pattern of lines – tells which elements are found

TYPES: 1. Mass spectroscopy – IDs atoms and molecules by their mass - forms ions which are sent through a magnetic or electric field - the path depends upon ratio of mass to its charge --- recorded on photographic plate

2. Atomic absorption spectroscopy (AAS) - determines heavy metal contaminants in air, water, soil samples; also, analyzing paint chips - measures amount of light of a specific wavelength absorbed by atoms of a particular substance

3. Ultraviolet (UV) spectroscopy - determines concentration of different elements in a solution Measures wavelengths of light; graph made compared to known for quantitative analysis Detects drugs in blood or urine; analyzes components of dyes & food additives; monitors air and water quality