ATR Prism Selection Criteria

Download PDF December 6, 2018

Introduction

ATR
ATR PRO ONE VIEW

ATR method is used to analyze the sample surface within 1~2 μm in depth. The measurement is collected when the ATR prism is in contact with the sample. In ATR method, the penetration depth of light into the sample for total reflection depends on the RI of prism and sample, incidence angle and wavelength. In addition, measurement range and durability depend on the material of the prism. Features of each prism are shown as follows. 

PrismRI (n1)Penetration Depth dp*1
(1000cm-1)
RI of Sample (n2)*2
for Total Reflection
Measurement Limit
in Low Wavenumber*3
Range
ZnSe2.4~ 2.0 μm<= 1.7~550 cm-1
Diamond2.4~ 2.0 μm<= 1.7~400 cm-1 *4
Ge4.0~ 2.0 μm<= 2.8~650 cm-1
PrismFeature of
Prism
Suitable SampleNon-Suitable SampleNotes
ZnSeGood
throughput
General organic
substance
Hard powder, acidalkaline,
high RI
sample
In case of hard
powder or hubbly
sample, diamond is
recommended
DiamondIntensity,
durability,
measurement
Hard powder, General
organic substance
High RI samplePoor S/N ratio in the
region around 2000
cm-1, due to internal
absorption
GeAnalysis for
high RI sample
Sample including carbonHard powder, acidalkalineWeak absorption
due to small depth of
penetration

*3 Case of measurement using ATR PRO 450-S, standard FTIR.
*4 If the measurement is needed in the wavenumber range below 400 cm-1, please contact local JASCO distributor.

Experimental

Figure 1. Suitable measurement example using ZnSe and Ge prism.
Sample: ethanol

Keywords

280AT0003-E, ATR, prism, diamond, Ge, ZnSe, refractive index

About the Author

Dr. Carlos Morillo received his Post Doc at Advanced Industrial Science & Technology in Fukuoka and was a Research Scientist at Kyushu University in Japan where he lived for several years. Carlos received his Doctor of Engineering from Kyushu University and his Masters and BS from Simon Bolivar University in Caracas Venezuela. He is an Applications Scientist at JASCO.