Phywe fibre-optics spectrophotometer

Menu in Datalyse:

Emission, e.g. the spectrum of a spectral lamp
Setup parameters... choose the time per scan and enter for each measuring.
Background, i.e. spectrum without light source
Reference, spectrum of a cell with water
Absorbance

The spectrophotometer is equipped with a CCD-array and is capable of measuring wavelengths in the interval 305 nm to 1050 nm. A fibre-optics cable 1.5 meters long transmits the light from the source to the device.

It is possible to measure absorbance, since it is possible to send the light of a built-in halogen lamp into an external cell holder with another fibre-optics cable.

The spectrophotometer can only scan the spectrum. It cannot measure at a specified wavelength. But a scan of 1024 values is measured in no more than 2 seconds (1 second). This way you get the entire spectrum on the screen. This sounds very good.

A measuring does take some time however since CCD are not without noise, i.e. they measure light even in darkness:

Emission:

1. Measure background (if the measuring time is changes, you have to measure the background again).
2. Measure Emission, the background (column 2 in the table) is subtracted.

Absorption:

3. Measure reference, i.e. measure on a cell containing water. The background is subtracted and the reference spectrum is written to column 3 of the table.
4. Measure absorbance. The absorbance is calculated using measured values and the reference.

Comments:

CCD's and fibre-optics cables are the future, there are some reservations about the device.

• A continual spectrum i.e. from a flashlight bulb or the built-in halogen lamp is not measured as continual but with strange peaks. This cannot be right!
• The spectrum of built-in lamp only go from about 450 nm to 900 nm, which means that you can only measure absorbance in this area.
• There are problems with some of the codes for serial communication.

Energy-saving light bulb + Hg-lamp

What gas(ses) does an energy saving bulb contain? Hg seems to be obvious.

Note that Datalyse is capable of displaying multiple graphs simultaneously now. For one thing you can select multiple columns for drawing a graph. For another you can choose between graph and table for 2 devices..

He-Ne laser