1000mm focal length vacuum spectrometer

One meter Seya-Namioka Monochromator

The Model 231 1-meter focal length Seya-Namioka uses simple grating rotation to scan wavelengths. An angle of 70° 15' subtends the entrance and exit slit arms. The focal length provides excellent resolution and a lot of work space. Stainless steel construction makes this design suitable for use with high vacuum and contaminant free experimental chambers or microchannel plate intensified detectors. The McPherson Model 231 Seya-Namioka features fixed entrance and exit slit positions as well as fixed beam direction from the exit slit. When used as a scanning spectrometer these valuable characteristics make the Model 231 suitable for use in applications at synchrotron storage rings. The Model 231M4 (231 version or revision 4) was designed specifically synchrotron applications. It offers white light bypass optics as well as diverting optics when the use of the spectrometer is required. Multiple grating turrets are employed to further simplify instrument demands during experiments.

Model 231 PDF Data Sheet

Specifications & Additional Information:

Optical DesignMcPherson Model 231 1-meter focal length f/23 Vacuum Monochromator
Angle between Slits70° 15'
Focal Length1-meter focal length Seya-Namioka design
Wavelength Rangerefer to grating of interest for range
Wavelength Accuracy+/-0.1-nm (on counter, with 1200 G/mm grating)
Wavelength Reproducibility+/- 0.005 nm (with 1200 G/mm grating)
Grating Size30 x 50-mm ruled area
Focal PlaneMultiply dispersion by the width of your detector for range

Performance with various diffraction gratings:

Grating (G/mm) (others available) 2400 1800 1200 600 300
Wavelength Range from 30-nm to 150nm 200nm 300nm 600nm 1.2um
Resolution (nm) at 313.1-nm 0.013 0.018 0.025 0.05 0.10
Dispersion (nm/mm) 0.42 0.55 0.83 1.66 3.33
Blaze Wavelength: (nm) Holo Holo Holo Holo Holo
80nm 150nm 150nm 700nm

* gratings work best from 2/3 to 3/2 the blaze wavelength

Outline Drawing Coming Soon

Select Publications

Abstract: Matrix interactions of rare‐gas oxide molecules formed in solid matrices were studied by photoluminescence.Excitation energies between 8–12 eV were provided by both synchrotron radiation at the Stanford Synchrotron Radiation Laboratroy (SSRL) and a hydrogen discharge source at UCSB. Photoluminescence emission and excitation spectra of Ar:CO2(1%), Kr:CO2(1%), Kr:N2O(1%), and Kr:O2(1%) mixtures were obtained. Radiative lifetimes of ArO and KrO emissions from CO2doped Ar and Kr matrices were also measured. The direct photodissociative threshold of CO2 to CO(X 1S+)+O(1 S) in an Ar matrix was found to be 10.6 eV, in agreement with that of the gas phase. Further unambiguous evidence for radiationless, dissociative energy transfer, between the matrix free exciton and CO2, probably by a harpooning mechanism, was seen in Kr:CO2 below the direct photodissociation threshold. Temperature, matrix annealing, and character of the photofragment were found to have significant effects on the rare‐gas oxide molecular binding and production rate.
R. V. Taylor, W. Scott, P. R. Findley, Zenglie Wu, W. C. Walker and K. M. Monahan
Abstract: Photoluminescence excitation, emission, and decay spectra were obtained for solid Xe:N2O and Kr:N2O mixtures using vacuum ultraviolet synchrotron radiation as the excitation source. The principal emitting species were determined to be XeO(1 D) and KrO(1 S) excimers. Fluorescence decay measurements indicate that the XeO(1 D) emission arises from two excited states.Analysis of the emission and excitation spectra leads to the conclusion that XeO(1 D) production follows nonradiative energy transfer to N2O from self‐trapped excitons in the xenon host.
K. M. Monahan and V. Rehn
Abstract: Photoluminescence excitation spectra of Ar:N2O (1%), Ar:OCS (1%), and Kr:OCS (1%) were obtained in the region 180–104 nm, using UVsynchrotron radiation at SSRL. Photodissociationenergy thresholds in the matrix were found to be: 8.06 eV for N2O→N2(X 1Σ+)+0(1 S) and 7.17 eV for OCS→CO (X 1Σ+)+S(1 S). Our results show several effects due to interactions between the matrix and the triatomic molecule: (1) differential blue shifts of the 1Π←1Σ+ and 1Σ+←1Σ+ transitions, (2) a greatly enhanced predissociation rate from 1Π to 1Σ+, (3) matrix dependent energy shifts of a particular Rydberg state, (4) nonradiative energy transfer between the matrix and the triatomic, involving either self‐trapped excitons and a Foster–Dexter mechanism or free excitons and a harpooning mechanism. To our knowledge, this is the first observation of the free exciton–harpooning mechanism in a rare gas matrix.
R. V. Taylor, W. C. Walker, K. M. Monahan and V. Rehn
Abstract: Optical electronic transitions were studied in the (CuInSe2)1−x−(2ZnSe)x system from 0.5 to 14 eV. The system crystallizes in the chalcopyrite structure for x≤0.43 and in the zinc-blende structure for x≥0.48. The absorption edge was found to be direct for all the compositions and the energy gap varies with x parabolically, without discontinuity at the structural transition. This dependence is associated with the substitutional disorder in the mixtures. Reflection measurements showed substantial differences between the compositions with the chalcopyrite structure and those with the zinc-blende structure. The additional peaks observed for the compounds with the chalcopyrite structure are ascribed to pseudodirect transitions which become allowed by zone folding. The optical constants in the visible and ultraviolet regions were determined from the reflection spectra by Kramers-Kronig analysis. The dependence of the absorption bands on composition and structure is discussed and possible assignments are suggested. The effective number of electrons per atom contributing, in the energy range studied, to optical transitions was calculated and was found to depend strongly on the amount of Cu d electrons in the mixture as well as on the crystal structure.
J. N. Gan, J. Tauc, V. G. Lambrecht, Jr., and M. Robbins

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