ZnSe is more stable in the presence of moisture as it is virtually not soluble in water. KBr is very sensitive and even small amounts of water are a problem.

hope this is helpful

Thanks for your reply. If there any disadvantage with ZnSe apart from this common/vitral issue.

the spectral transmission window of KBr is larger. you may have limited transmission in ZnSe at wavenumbers below ~650 cm-1

Thanks again. if we want to concentrate on 600 to 4000 cm-1 range,then ZnSe is better or Kbr? Because our aim is to keep the machine in ambient environment where the rel. humidity is around more than 70% for at least 8 months within a year!

for many applicationsit doesn't really matter if you have a spectral window down to 500 or 650 cm-1, but in some cases having this extra 150 cm-1 is crucial. so regardless of the humidity, it depends a bit on the materials you want to study. 

most instruments have an internal heating system and adsorptive agents to ensure that no water condenses inside and to avoid spectral interference from water absorption lines. when the humidity is that high in your lab it may be an option to additionally purge the instrument with dry air or nitrogen (or if you want to spent heaps of money you can go for a vacuum instrument).

Thanks a lot for your suggestions. Actually for my case below 600 cm)1 bands are not much crucial. Rather it is very important to keep the beam splitter safely under such high humid environment. Although I can cut down to 40%,spectrometer keeping place. Let me discuss little more specific: My main idea to get the following three facilities:

1) Normal mode (transmission mode) operations /temperature dependent FT-IR study

2) Grazing incidence

3) ATR mode

So keeping into consideration of ZnSe beam splitter which model/brand is best suitable?it would be great if you email me the model number and brand information's just to avoid open debate. My id: [email protected]

I'd buy the beam splitter from the manufacturer of the instrument to ensure that it fits perfectly

okay. May I request your email ID,so that I will ask few questions before buying.

If you still need the FTIR spectrometer, you may contact Mr. Sougata Mukherjee, LabIndia.. They are the authorized distributor of Bruker FTIR machines... Most importantly, they are located in SP Banerjee road... He will demonstrate the machine at your location... Instead of ZnSe crystal, you may opt for diamond ATR crystal....