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.
|Prism||RI (n1)||Penetration Depth dp*1
|RI of Sample (n2)*2
for Total Reflection
in Low Wavenumber*3
|ZnSe||2.4||~ 2.0 μm||<= 1.7||~550 cm-1|
|Diamond||2.4||~ 2.0 μm||<= 1.7||~400 cm-1 *4|
|Ge||4.0||~ 2.0 μm||<= 2.8||~650 cm-1|
|Suitable Sample||Non-Suitable Sample||Notes|
|Hard powder, acidalkaline,
|In case of hard
powder or hubbly
sample, diamond is
|Hard powder, General
|High RI sample||Poor S/N ratio in the
region around 2000
cm-1, due to internal
high RI sample
|Sample including carbon||Hard powder, acidalkaline||Weak absorption
due to small depth of
*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.
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.