Harrick Scientific offers single-pass trapezoids for parallelepiped infrared ATR spectroscopy. SPT and SPP ATR crystals are available in Si, Ge, ZnSe. Our stock sizes are listed below. We welcome the opportunity to quote on other sizes and materials to meet your requirements.
IR Optical Materials for SPP-ATR Plates
| n | KH (psi) | MOR* (psi) | useful range cm-1 (μm) | chemical properties | ||
|---|---|---|---|---|---|---|
| Windows 1-2mm | IRE 70mm | |||||
| Ge | 4.0 | 550 | 7000 | 5000-600 (2.0-17) |
5000-900 (2.0-11.4) |
Insoluble in water, soluble in hot H2SO4, aqua regia |
| Si | 3.42 | 1150 | 9000 | 10,000-100 (1.0-100) |
9500-1500; 350-FIR (1.06-6.7 30-FIR) | Insoluble in most acids and bases; soluble in HF and HNO3 |
| ZnS | 2.22 | 355 | 10,000 | 22,000-750 (0.45-14.0) |
14,000-1000 (0.7-10) |
Soluble in acid; insoluble in water |
| ZnSe | 2.42 | 150 | 8000 | 20,000-500 (0.5-20) |
20,000-700 (0.5-14.3) |
Soluble in strong acids; dissolves in HNO3 |
| n: Refractive IndexKH: Knoop HardnessMOR: Rupture Modulus | ||||||
ATR Plates Specifications
The dimension of an internal reflection (ATR) element (IRE) is given by its length (l), width (w), and thickness (t). The length of the IRE, measured from the center of the entrance aperture to the center of the exit aperture, determines the number of reflections, N.
N = ( l / t ) tan θ
If l is kept constant, plates of a different thickness can be exchanged without the necessity of realigning the accessory.
Note that for l = 50 mm and θ = 45° degrees, the tip-to-tip length, l ( t - t ) = l + t. This length is 52 mm for t = 2 and 51 mm for t = 1 mmm.