Multiple Transmission−Reflection Infrared Spectroscopy for High-Sensitivity Measurement of Molecular Monolayers on Silicon Surfaces

Abstract

A new infrared spectroscopic measurement involving multiple transmissions and reflections for molecular monolayers adsorbed on silicon surfaces has been established. Compared to the well-known multiple internal reflection (MIR) method, the distinctive advantage of multiple transmission-reflection infrared spectroscopy (MTR-IR) is the convenient measurement using standard silicon wafers as samples, while in the MIR setup special fabrication of geometric shapes such as 45 degrees bevel cuts on an attenuated total reflection silicon crystal is needed. Both p- and s-polarized spectra can be obtained reproducibly with the same order of sensitivity as by the MIR spectroscopy. Optimal conditions for spectral acquisition have been obtained from theoretical calculations. The ability of this methodology to gather high quality infrared spectra of adsorbed monolayers is demonstrated and the analysis of the surface packing and molecular orientation is discussed.

Ultrathin, freestanding, stimuli-responsive, porous membranes from polymer hydrogel-brushes

“…25,26 As displayed in Fig. After APTES deposition, the presence of an organic layer with 0.4 ± 0.1 nm thickness was recorded.…”

Microwave irradiated click reactions on silicon surfaces via derivertization of covalently grafted poly(PEGMA) brushes

“…Spectral resolution and scan number were set at 4 cm À1 and 100 scans respectively. A unique accessory for Multiple Transmission-Reflection Infrared Spectroscopy (MTR-IR) [40,44,45] designed by our group was used to increase the spectral signal-tonoise ratio. It helps us to achieve sensing any slight surface changes [40,46].…”

Construction of multiple generation nitriloacetates from poly(PEGMA) brushes on planar silicon surface for enhancement of protein loading

“…The new contribution from succinic ester and succinic acid is the cause for both intensity enhancement and blue‐shift. Overall, polymer brushes elucidate a higher density of carboxyl groups than on a molecular monolayer prepared by coupling undec‐10‐enoic acid on SiH 47, 48. In addition, we showed the strong absorption band of SiO stretching between 1150 and 1200 cm −1 in Fig.…”

“…Air was exhausted from the sample compartment to eliminate CO 2 and water vapor absorptions. In order to improve the sensitivity of IR measurements, a home‐built accessory for MTR‐IR 47, 48 was adopted. Baselines of some spectra were corrected for easier demonstration.…”