ODA LLC : Spectrophotometry

[ Spectrophotometry ]

Spectrophotometry is a technique that determines how materials interact with light as a function of wavelength and other attributes of both the material and the light. In contrast to spectrofluorometry, the dispersion performed by the monochromator or interferometer takes place either between the source and the sample or between the sample and the detector, not in both locations. We describe each of these properties and the range of these properties that ODA can address with its four major spectrophotometers.

Wavelength Range

Instrument	Nanometer (nm) Range		Micron (µm) Range		Wavenumber (1/cm) Range
Cary/Varian 5000 [new] Dispersive UV-Vis-NIR	180	3,300	0.18	3.3	55,556	3,030
Cary/Varian 500E Dispersive UV-Vis-NIR	180	3,300	0.18	3.3	55,556	3,030
Perkin-Elmer 983G Dispersive IR	2,000	56,000	2.0	56.0	5,000	180
Nicolet 560 FT-IR Fourier Transform IR	2,000	25,000	2.0	25.0	5,000	400

Optical Arrangement

Instrument	Layout	Sources	Sample Compartment	Detectors
Cary/Varian 5000 Dispersive UV-Vis-NIR	Sources-double monochromator-sample-detectors	Tungsten-halogen/ deuterium	Double-beam, focus in center	Photo- multiplier, cooled PbS
Cary/Varian 500E Dispersive UV-Vis-NIR	Sources-double monochromator- sample-detectors	Tungsten- halogen/ deuterium	Double-beam, focus in center	Photo- multiplier, cooled PbS
Perkin-Elmer 983G Dispersive IR	Source-sample- monochromator- detector	Globar™	Double-beam converging	Thermocouple
Nicolet 560 Fourier Transform IR	Sources-interfero- meter-samples- detector	Globar™/ tungsten-halogen	Single-beam- collimated	DTGS

Orientation

Transmittance	Angle		Reflectance	Angle
	Incident	Exitent		Incident	Exitent
Normal Direct [Specular] Absolute	0°	0°	Near-Normal Specular Absolute	7°	7°
Variable Angle Direct [Specular] Absolute	0 - 75°	0 - 75°	Variable Angle Specular Referenced	20° - 75	20° - 75°
Normal Total Absolute	0°	2π sr Forward	Near Normal Total Referenced	7°	2π sr Backward
Variable Angle Total Absolute	0 - 75°	2π sr Forward	Variable Angle Total Referenced	0° - 75°	2π sr Backward

Polarization

The incident beams from all three instruments is somewhat polarized due to the presence of gratings and non-normal reflections in the optical train. The parallel - p - and perpendicular - s - polarizations can be specified and isolated with polarizers over the 0.18 < λ < 3300 nm spectral range.

ODA does not presently own IR polarizers for λ > 3300 nm, so polarization cannot be controlled in this wavelength range.