Spectrophotometry

Spectrometer

Generates light at specific individual wavelengths across electromagnetic spectrum.

Photometer

Measures light intensity transmitted through or absorbed by sample solution.

Primary Application

Determines concentration of unknown solutes, purity levels, and reaction kinetics.

Incident Light Power

Total monochromatic light intensity emitted from source toward cuvette.

Absorbed (A)

Photon energy absorbed by solute molecules to induce electronic transitions.

Transmitted

Unabsorbed light exiting cuvette sample cell onto photodetector surface.

1.0

Transmittance values range from 0.0 to _________ (or 0% to 100%).

exponentially

Transmittance decreases ____________ as absorbing solute concentration increases.

100%

Pure solvent is set to ________ T (I = I0) to offset reflection and solvent absorption.

Light Source

Polychromatic radiant beam emission.

Monochromator

Isolates single monochromatic wavelength.

Sample Cuvette

Standardized cell containing solution.

Photodetector

Converts light energy to electric signal.

Digital Display

Amplifies and computes Abs/ %T.

Deuterium Arc Lamp

Continuous ultraviolet radiation emission. Essential for protein and nucleic acid

quantification.

Tungsten Lamp

High stability halogen filament emitting continuous light across visible and near-infrared regions.

Xenon Flash Lamp

High energy pulsed broad-spectrum source spanning both UV and Visible regions in modern units.

Entrance Slit

Narrows incoming light beam into narrow parallel rays.

Monochromator

Separates broad polychromatic light into constituent spectral wavelengths via diffraction.

Exit Slit

Blocks unwanted spectrum and passes selected narrow wavelength band.

Diffraction Grating

Separates broad polychromatic light into constituent spectral wavelengths via

diffraction.

Quartz / Silica

UV & Visible Analysis

Borosilicate Glass

Visible Spectrum Only

Plastic / PS

Disposable Vis Routines

Photomultiplier Tube (PMT)

Multiplies photoelectrons via dynodes. High sensitivity for ultra-low intensity signals.

Silicon Photodiode

Generates linear electric current proportional to light power. Highly durable and compact.

Photodiode Array (PDA)

Measures all wavelengths simultaneously. Enables instantaneous full spectrum scanning.

Molar Absorptivity

Measures how well a compound absorbs a given wavelength of light