Use of glass cell in the UV region
Posted: Sat Sep 03, 2005 12:31 pm
by Ricardinio
I read that the use of glass cell in the UV region might be a source of error.
Does this mean that Glass absorb too much in this region? What about performing and substracting a blank?
What is specific with quartz cell for UV measurements?
I would appreciate your comments.
Posted: Sat Sep 03, 2005 6:48 pm
by tom jupille
Depends on the glass.
The UV cutoff wavelength of glass is primarily composition dependent. Pure silica (100% SiO2) glass can have a UV cutoff below 200 nm, while glasses containing, for example, ceria (CeO2) or titania (TiO2), will shift the cutoff to wavelengths below 380. If enough of these oxides are added the cutoff will shift to wavelength below 400 nm which will manifest itself as a coloration of the glass as the blue end of the visible spectrum is absorbed along with the UV.
http://en.wikipedia.org/wiki/Talk:Glass ... _confusion
"Quartz" cells are actually "pure silica" as referenced above.
Posted: Tue Sep 06, 2005 4:39 pm
by Mark Tracy
When your working wavelength is near or below the UV cutoff, you will have insufficient light for accurate work. (UV cutoff is usually defined as the wavelength below which 90% or more of the light is blocked.) The noise will be severe, the linear range will be very restricted.