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NICODOM Ltd. Department FTIR Parts and Accessories |
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Instrument Selection
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NICODOM IR Transmission windows - Germanium Those transmission windows are made from
optical grade Germanium. Germanium is a common material in ATR spectroscopy
but has been rarely used in transmission. The windows are uncoated. Nicodom Germanium windows feature the
following advantages: - Mechanically resistant - Inert - Water, Acids, Bases, Solvents - Suitable for water/corrosive samples,
student labs - Suitable for standard and special
experiments The current offer (clearance sale) includes only one window size: Round windows 20mm diameter and aproximatelly 1mm thick (thickness may vary). You can choose between first quality or second quality (strongly discounted) windows. The discounted windows have some cosmetic imperfections at their edges. Those imperfections do not influence the spectroscopic quality. First Quality
Second Quality (cosmetic imperfections on edges)
Most chemical compounds exhibit characteristic infrared spectra,
depending on their molecular symmetry, atomic weights and bond strength. This
is an advantage when IR is used for unknown compounds identification, but could
be a disadvantage when seeking window materials, which are desired not to
have infrared spectrum. Such materials are rare and have several
disadvantages. Traditional window materials used in IR spectroscopy are
hygroscopic (KBr, NaCl, CsI), fragile, chemically not resistant, expensive
(diamond), or are totally absorbing in a part of infrared region (CaF2,
SiO2). Germanium is one from possible IR spectroscopy materials which is
often used for ATR technique, but has not been used for transmittance measurements
so frequently yet. NICODOM with its over 10 years long experience in FTIR
spectroscopy recommends you Germanium as an excellent infrared window
material, because it is overcoming the main mentioned disadvantages: it is
not hygroscopic and is chemically very resistant, resists thermal and
mechanical shocks, scratching and fogging and is inexpensive. However,
silicon exhibits relatively high refractive index and is not transparent in
visible region. Material
data
- Transmission: 5500-600
cm-1 - Refractive Index: 4 - % Transmission (at
2000cm-1): 50% by 2mm thickness - Solubility in water,
solvents, acids and basis: insoluble (except of hot H2SO4 and aqua regia) - Melting point: 930 C - Hardness (Knoop): 550
kg/mm2 The infrared spectrum of optical grade Germanium window shows that
this material is transparent in the standard middle infrared spectral region.
Picture 1: Infrared spectrum of single NICODOM Ge window in
transmittance scale.….…, spectral range 4000-400 cm-1, FTIR Nicolet Avatar
360 (air as background, Ge window as sample) Picture 2: 100% line of single NICODOM Si window in transmittance
scale…….., spectral range 4000-400 cm-, FTIR Nicolet Avatar 360 (Ge window
collected as background and sample) |
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