Firma:              Spectra Physics

Modell:            Spectra 200

Kommentar:   Dokumente engl.

Spectra 200 UV-Vis DETECTOR

Specifications:

Wavelength Range:

190-800 nm with standard Deuterium and Tungsten lamps.

Band Width:

6 nm

Wavelength Accuracy:

+ 1nm

Wavelength Precision:

+0.1nm

Optical Methodology:

Standard Deuterium lamp (190-365 nm) and Tungsten lamp (366-800 nm) light sources with concave hob graphic grating monochromator with double-beam optics, and provi­sions for purging the monochromator.

Range Selections:

0.0005 to 7.9995 AUFS, in 0.0005 AU incre­ments on any of the recorder outputs.

Absorbance Ratio:

Displayed as ratio of absorbances (at the two selected wavelengths) per full-scabe range; plotted "as 10g of ratio of absorbances per full-scale range.

Recorder Outputs:

10 mV, 100 mV, or 1.0 V output in any com­bination on the four recorder outputs.

Integrator Output: .

5 V per AU (2 AU/V).

Remote Controls:

Rear panel input for Auto Zero and external RUN; RS-232-C serial Interface for computer control and/or data acquisition; DPDT relay closure for optional auto-scan valve control -and/or peak-detection driven fraction collector.

Noise : < + 1.0 x 10 ^-5 AU at 254 nm with 1.0 sec rise time.

< + 1.0 x 10 ^-5 AU at 546 nm with 1.0 sec rise time.

Drift:

<2 10-4 AU/hour after 1 hour warmup.

Zero Adjust:

Plus or minus any amount by auto zero or by man­ual entry.

Rise Time Filter:

Digital active filter with rise times selectable from 0.0 to 9.9 sec (divide by 2 to convert to an equivalent time constant).

Flowcells:

Pathlengths from 10 mm to 0.0 mm, cell volumes from 0 to 15 microliters, stainless steel, titanium, or Kel-Fee" contact materials, sapphire Windows. 1000 psi pressure rating for stainless steel cells, 500 psi pressure rating for Kel-F cells, 2,000 psi pressure rating for variable pathlength preparative cells; 7,000 psi pres­sure rating for high pressure microbore cell.

OVERVIEVV

The light sources are continuum lamps that jointly provide consistent intensity across the entire spectrum from 190 to 800 nm. Two baffles are used to minimize stray light. Wavelength selection is provided by a concave holographic grating actuated by a microprocessor-controlled stepper motor.

True double beam operation is provided by a fiberoptic beam split­ter. A reference photodiode continuously monitors the light from one leg of the beam splitter. The other leg is imaged by a Jens through a sample cell onto the sample photodiode.

The photodiodes are connected to individual pre-amplifiers. The pre-amp output voltages are directly proportional to the light inten­sity at the photodiode active surfaces (Fig. 7.2). The output of the pre-amplifiers is sent to an analog-to-digital converter (A/D) .

The analog-to-digital (A/D) converter converts the photodiode pre­amplifier Outputs to provide a nineteen (19) bit digital word. Ap­proximately 10 readings are taken per second. The digitized data are processed by the microcomputer where all filtering and ranging is carried out. The processed data are transferred to a digital-to analog (D/A) converter to provide a linear -2 V to +2 V fall scale output for each Integrator and a -1 to +1 V fall scale output for each recorder channel.

Sense lines from the Computer to the AUTO ZERO and external RUN connections provide flexibility for remote and/or automatic operation. The keyboard an the front panel allows direct Operator control over all Instrument functions.

An RS-232-C Interface allows remote control of all parameters used or-controlled by the computer. In addition, status information and either raw or processed data can be transmitted through the inter­face.

Light from either the Tungsten (W) or Deuterium (Dz) lamp is se­lected by a shutter, passed through a set of baffles, and dispersed by a concave holographic grating. After passing through a second set of baffles, the light is transmitted to a fiber optic beam Splitter creating reference and sample beams. The reference beam is di­rected to a photodiode, while the sample beam is focused by a lens, passed through a flowcell, and terminated upon a sample photodiode.

Detector Optical System: