200mm focal length monochromator / spectrometer, McPherson Model 272

Model 272 High Throughput f/2 Monochromator

The Model 272 monochromator contains a large, 100-mm diameter diffraction grating. This guarantees a large solid angle of light collection. The gratings corrected design reduces optical aberrations. This improves the spectral resolution of this high throughput optical system. The Model 272 is a versatile research grade monochromator. It delivers high throughput and moderate spectral resolution. Usable in any attitude, standard features of much larger McPherson monochromators have found home in this high efficiency f/2 monochromator.

An example of a Model 272 in use for cathodoluminesce (CL) imaging and spectroscopy of geologic materials is described on the National Museum of Natural Histories, Department of Mineral Sciences web page

Model 272 PDF Data Sheet

Specifications & Additional Information:

Optical DesignNormal Incidence
Focal Length200 mm
Aperture Ratiof/2 (NA 0.5)
Wavelength Rangerefer to grating of interest for range
Wavelength Accuracy2nm (on mechanical counter with 1200g/mm grating)
Wavelength Reproducibility0.1nm (with 1200g/mm grating)
Grating Size104mm diameter
SlitsContinuously variable micrometer actuated width 0.01 to 4 mm, height settings from 2 to 20 mm
Angle between Entrance and Exit beams38 degrees
Focal Plane25mm, multiply dispersion by the width of your detector for range

Performance with various diffraction gratings:

Grating Groove Density (g/mm) 2280 1140 570
Spectral Resolution at 312.6nm (nm, FWHM) 0.7 1.6 3.7
Reciprocal Linear Dispersion (nm/mm) 2 4 8
Wavelength Range from 185nm to * 650 1250 2500

Outline Drawing

McPherson Model 272 200mm f.l. Spectrometer

Select Publications

Abstract: The application of UV photoacoustic spectroscopy to the evaluation of UV-absorbing paint additives in clear paint layers is described. This technique enables the quantitative analysis of additive concentration and aids in determining the effects due to paint processes and substrate composition changes on additive concentration. The inclusion of photoacoustic phase information is essential to offset the saturation effects that dominate these strongly absorbing samples. Two analysis techniques are evaluated, both of which partially or totally utilize the phase data. When comparisons between samples on substrates with different heat capacities are needed, the phase-only method is preferred. Otherwise, the two methods give comparable results. Using these methods, two different paint/substrate/additive systems are easily evaluated for changes in process or changes in substrate materials. The instrumentation and interpretation methods are discussed in detail.
Roscoe O. Carter, III
Abstract: Herein we analyze experimentally the effect that introducing highly reflecting photonic crystals, operating at different spectral ranges, has on the conversion efficiency of dye sensitized solar cells. The interplay between structural colour and cell performance is discussed on the basis of the modified spectral response of the photogenerated current observed and the optical characterization of the cells. We demonstrate that, with the approach herein discussed, it is possible to achieve relatively high efficiencies using thin electrodes while preserving transparency. At the same time, the appearance of the device can be controllably modified, which is of relevance for their potential application in building integrated photovoltaics (BIPV) as window modules.
Daniele Colonna,a Silvia Colodrero,b Henrik Lindström,c Aldo Di Carloa and Hernán Míguez*b
Abstract: A two-compartment photoelectrochemical cell consisting of a CdS photoanode immersed in aqueous sulfide solution, Nafion membrane, platinum cathode and sulfuric acid solution as the dark-compartment electrolyte was constructed. The effects of the concentrations of the electrolytes, membrane surface and cathode materials on the performance of the cell were studied to reach high quantum yield of hydrogen production. Under optimized conditions, light to hydrogen conversion efficiency up to 12% was observed under sun light illumination.
Grzegorz Milczareka, Atsuo Kasuyab, Sergiy Mamykinb, T. Araib, K. Shinodab, K. Tohjib
Abstract: Photoacoustic Spectroscopy (PAS) experiments in the visible and ultraviolet regions of the electromagnetic spectrum were carried out on a variety of tourmaline species. The results of our investigation show that PAS can be seen as a powerful alternative spectroscopic tool in the identification and characterization of color centers in mineral specimens.
R.J.S. Lima1, A.S. Vasconcelos1, R.R. Wegner2 and J.F. Suassuna1
Abstract: Composite structures of Ru(bpy)2(4,4′-(PO3H2)2bpy)2+ surface bound to nanocrystalline TiO2 with an overlayer of Ru(bpy)32+ ion exchanged into Nafion, FTO|nanoTiO2-[Ru(bpy)2(4,4′-(PO3H2)2bpy)]2+/Nafion,Ru(bpy)32+ (FTO = fluorine-doped tin oxide), have been prepared and characterized. Steady-state emission and time-resolved lifetime measurements demonstrate that energy transfer occurs from Nafion,Ru(bpy)32+* to adsorbed Ru(bpy)2(4,4′-(PO3H2)2bpy)2+ with an efficiency of ∼0.49. Energy transfer sensitizes photoinjection by the adsorbed metal-to-ligand charge transfer (MLCT) excited state by an “antenna effect.”
Paul G. Hoertz ‡, Anna Goldstein , Carrie Donley §, and Thomas J. Meyer
Abstract: Porous silicon samples have been prepared from p-type single-crystal silicon 〈100〉 by a galvanostatic and an open-circuit etch in 50% HF. The materials display bright red-orange room-temperature photoluminescence (PL) in air and toluene solution. Infrared measurements show that the porous silicon surface is partially oxidized. Exposure to anthracene (An) or 10-methylphenothiazine (MPTZ) results in dynamic quenching of the material's excited state(s). Nanosecond time-resolved PL decays are complex and wavelength dependent, with average lifetimes in neat toluene of 0.3−16 μs. Quenching by An and MPTZ is more efficient and rapid at short observation wavelengths. The steady-state and time-resolved quenching data are well fit to the Stern−Volmer model. The PL decays are well described by a skewed distribution of recombination rates.
Minh C. Ko and Gerald J. Meyer

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