Temperature Dependence of the 1727 cm^–1 Interstitial Oxygen Absorption Band Studied by Attenuated Total Internal Reflection Infrared Spectroscopy in a Newly Developed Microreactor

Abstract

In this work we study oxygen interstitial defects (O i ) in a silicontechnology-based microreactor with an integrated attenuated total internal reflection (ATR) crystal as a function of an externally applied potential by means of attenuated total internal reflection infrared spectroscopy (ATR-IR). A reduction of the 1727 cm −1 O i IR absorption band is observed with increasing potential. We evidence that this band is related to the presence of O i , which enables detection of O i by ATR-IR spectroscopy.The observed reduction with increasing potential is ascribed to an increase in temperature, due to resistive heating of the silicon.

Electrochemical ATR-SEIRAS Using Low-Cost, Micromachined Si Wafers

“…It is typically explained as a combination band of the 1108 cm –1 Si–O–Si asymmetric stretch and transverse acoustic and optical phonon modes . However, recent evidence suggests that this band may be better explained as a combination mode that does not involve the asymmetric Si–O–Si stretch . The optical transparency of silicon can be improved somewhat by employing more expensive FZ rather than CZ silicon, but it is clear from Figure that the intrinsic character of silicon requires smaller optical path lengths to prevent near total extinction of light with wavelengths longer than ca.…”

Catalytic cracking of 1, 3, 5-triisopropylbenzene over silicoaluminophosphate with hierarchical pore structure

“…The absorption band at 460 cm -1 [29]. At 3460 cm -1 there is a contribution from OH stretching of silanols that is hydrogen bonded to the oxygen of neighbouring silanols of the mesoporous SAPO-5 composite [30], and the absorption band at 1638 cm -1 is assigned to the vibration of the lattice water [31]. Meanwhile, it is observed that the absorption band at 720 cm -1 is in good agreement with the SAPO-5 absorption band which represents the symmetric vibration of the PO 4 or AlO 4 tetrahedron [32].…”

Modular microreactor with integrated reflection element for online reaction monitoring using infrared spectroscopy

“…1,2 In a review by Jensen et al it is stated that for microreactors to be applicable to more than laboratory applications, sensors must be integrated into the systems. Now, almost 20 years later, only a limited amount of papers have been published regarding online reaction monitoring in microfluidic microreactors, most notably the work by or in association with the groups of H. Gardeniers, [3][4][5][6][7] K. Jensen 2,8 and several others. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] These techniques for direct online measurement operate using different types of sensors, such as mass-spectrometry, 14 fluorescence and UV/vis spectroscopy, 10,15,18,19,21 electrochemistry 4,16,17 and IR/NIR spectroscopy.…”

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22] These techniques for direct online measurement operate using different types of sensors, such as mass-spectrometry, 14 fluorescence and UV/vis spectroscopy, 10,15,18,19,21 electrochemistry 4,16,17 and IR/NIR spectroscopy. 3,5,7,9,[11][12][13]20,22 These reported works are often geared towards a specific application and do not expand to broader fields. In our group, we have obtained ample expertise with (modularly designed) microreactor systems.…”

“…In literature, hyphenated ATR-FTIR with microfluidic reaction chambers 3,5,7,12,13 is described. Although these microfluidic devices are well designed, they might be difficult to replicate outside the research group, due to the highly specific and somewhat complex reaction chamber designs.…”