The model 20 uses the the new DeSa subtractive double grating monochromator for selecting and scanning the wavelengths. This tiny 7-sided monochromator uses two huge 40 x 45 mm gratings for outstanding light throughput, even down to the lowest wavelengths. These holographically blazed gratings can be for ultraviolet, UV/Vis, visible, Vis-NIR, or NIR. All associated light sources and detectors will be selected by Olis to be compatible with this blazed grating range. The spectral resolution is 0.5-5 nm, based on the slit width used; slits are interchangeable fixed slits of 0.5, 0.6, 1.24, and 2 mm wide, with other sizes available by special request. Like the Olis DSM 17, it can be enhanced to support scanning (or fixed wavelength) excitation and fixed wavelength emission; it is slightly superior to the model 17 in its excitation intensity performance.
| Gratings |
Spectral Range |
Wavelength Resolution |
Applications |
Detectors |
| The gratings are optics which determine the spectral range, wavelength resolution, and applications. Easily accessed and changed in the Olis DSM 20 spectrophotometer |
The spectral range is fixed by the gratings. Gratings in the Olis Hummingbird monochromator can be changed with a minute’s effort. |
The bandpass sets spectral resolution, which is determined by the gratings and slits used.
Wavelength resolution for two slit widths are presented; slit widths optionally available are 0.280, 0.600, 0.760, 1.24, 1.56, 3.62 mm. |
Secondary structure determination mandates first grating pair (usual range for a protein is 260-190 nm, or to 185, 180, or 175 nm if the sample preparation permits). |
For Digital Subtractive CD, fast and sensitive detectors are used. PMTs are useful from UV to around 850 nm; InGaAs detectors with Olis fast response electronics are used from ~600-1650 nm |
1200 lines/mm;
blaze  = 250 nm |
167-720 nm |
with 0.12 mm slit, 0.5 nm
with 0.5 mm slit, 2 nm |
Secondary protein structure determination; tertiary structure information |
Photomultiplier tubes (PMTs) |
| 1200 lines; 350 nm |
250-800 nm |
with 0.12 mm slit, 0.5 nm,
with 0.5 mm slit, 2 nm |
Tertiary protein structure information |
PMTs |
| 800 lines; 600 nm |
350-1200 nm |
with 0.12 mm slit, 0.7 nm
with 0.5 mm slit, 3 nm |
Nanostructures, Polymers, Metal ion chelation |
PMTs and InGaAs |
| 600 lines; 750 nm |
400-1650 nm |
with 0.12 mm slit, 1 nm
with 0.5 mm slit, 4 nm |
Nanostructures, Polymers, Metal ion chelation |
PMTs and InGaAs |
