Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts

Paul M Donaldson; Russell F Howe; Alexander P Hawkins; Mike Towrie; Gregory M Greetham

doi:10.1063/5.0139103

Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts

Paul M Donaldson, Russell F Howe, Alexander P Hawkins, Mike Towrie, Gregory M Greetham

Chemistry

Rutherford Appleton Laboratory

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

3 Downloads (Pure)

Abstract

Solid, powdered samples are often prepared for infrared (IR) spectroscopy analysis in the form of compressed pellets. The intense scattering of incident light by such samples inhibits applications of more advanced IR spectroscopic techniques, such as two-dimensional (2D)-IR spectroscopy. We describe here an experimental approach that enables the measurement of high-quality 2D-IR spectra from scattering pellets of zeolites, titania, and fumed silica in the OD-stretching region of the spectrum under flowing gas and variable temperature up to ∼500 ◦C. In addition to known scatter suppression techniques, such as phase cycling and polarization control, we demonstrate how a bright probe laser beam comparable in strength with the pump beam provides effective scatter suppression. The possible nonlinear signals arising from this approach are discussed and shown to be limited in consequence. In the intense focus of 2D-IR laser beams, a free-standing solid pellet may become elevated in temperature compared with its surroundings. The effects of steady state and transient laser heating effects on practical applications are discussed.

Original language	English
Article number	114201
Journal	The Journal of Chemical Physics
Volume	158
Issue number	11
Early online date	15 Mar 2023
DOIs	https://doi.org/10.1063/5.0139103
Publication status	Published - 21 Mar 2023

Bibliographical note

ACKNOWLEDGMENTS
This work was supported by a UKRI Future Leaders Fellowship grant (Grant No. MR/S015574/1), STFC-UKRI program access to CLF-ULTRA (Grant No. LSF1828), direct access to CLF-ULTRA (Grant Nos. Apps 17330043 and 19130012), and a group residency in the Research Complex at Harwell (RCaH). The authors are grateful to Kathryn Welsby, Ivalina Minova, and Santhosh Matam for support early in the project with samples and the Linkam cell. Mr. John Still of the School of Geosciences, University of Aberdeen is thanked for the SEM images, and Kieran Farrell/Martin Zanni is thanked for the discussion about the polarizations of the beams creating the thermal transients

Data Availability Statement

The data that supports the findings of this study are available from the corresponding author upon reasonable request

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Cite this

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title = "Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts",

abstract = "Solid, powdered samples are often prepared for infrared (IR) spectroscopy analysis in the form of compressed pellets. The intense scattering of incident light by such samples inhibits applications of more advanced IR spectroscopic techniques, such as two-dimensional (2D)-IR spectroscopy. We describe here an experimental approach that enables the measurement of high-quality 2D-IR spectra from scattering pellets of zeolites, titania, and fumed silica in the OD-stretching region of the spectrum under flowing gas and variable temperature up to ∼500 ◦C. In addition to known scatter suppression techniques, such as phase cycling and polarization control, we demonstrate how a bright probe laser beam comparable in strength with the pump beam provides effective scatter suppression. The possible nonlinear signals arising from this approach are discussed and shown to be limited in consequence. In the intense focus of 2D-IR laser beams, a free-standing solid pellet may become elevated in temperature compared with its surroundings. The effects of steady state and transient laser heating effects on practical applications are discussed. ",

author = "Donaldson, {Paul M} and Howe, {Russell F} and Hawkins, {Alexander P} and Mike Towrie and Greetham, {Gregory M}",

note = "ACKNOWLEDGMENTS This work was supported by a UKRI Future Leaders Fellowship grant (Grant No. MR/S015574/1), STFC-UKRI program access to CLF-ULTRA (Grant No. LSF1828), direct access to CLF-ULTRA (Grant Nos. Apps 17330043 and 19130012), and a group residency in the Research Complex at Harwell (RCaH). The authors are grateful to Kathryn Welsby, Ivalina Minova, and Santhosh Matam for support early in the project with samples and the Linkam cell. Mr. John Still of the School of Geosciences, University of Aberdeen is thanked for the SEM images, and Kieran Farrell/Martin Zanni is thanked for the discussion about the polarizations of the beams creating the thermal transients",

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N1 - ACKNOWLEDGMENTS This work was supported by a UKRI Future Leaders Fellowship grant (Grant No. MR/S015574/1), STFC-UKRI program access to CLF-ULTRA (Grant No. LSF1828), direct access to CLF-ULTRA (Grant Nos. Apps 17330043 and 19130012), and a group residency in the Research Complex at Harwell (RCaH). The authors are grateful to Kathryn Welsby, Ivalina Minova, and Santhosh Matam for support early in the project with samples and the Linkam cell. Mr. John Still of the School of Geosciences, University of Aberdeen is thanked for the SEM images, and Kieran Farrell/Martin Zanni is thanked for the discussion about the polarizations of the beams creating the thermal transients

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N2 - Solid, powdered samples are often prepared for infrared (IR) spectroscopy analysis in the form of compressed pellets. The intense scattering of incident light by such samples inhibits applications of more advanced IR spectroscopic techniques, such as two-dimensional (2D)-IR spectroscopy. We describe here an experimental approach that enables the measurement of high-quality 2D-IR spectra from scattering pellets of zeolites, titania, and fumed silica in the OD-stretching region of the spectrum under flowing gas and variable temperature up to ∼500 ◦C. In addition to known scatter suppression techniques, such as phase cycling and polarization control, we demonstrate how a bright probe laser beam comparable in strength with the pump beam provides effective scatter suppression. The possible nonlinear signals arising from this approach are discussed and shown to be limited in consequence. In the intense focus of 2D-IR laser beams, a free-standing solid pellet may become elevated in temperature compared with its surroundings. The effects of steady state and transient laser heating effects on practical applications are discussed.

AB - Solid, powdered samples are often prepared for infrared (IR) spectroscopy analysis in the form of compressed pellets. The intense scattering of incident light by such samples inhibits applications of more advanced IR spectroscopic techniques, such as two-dimensional (2D)-IR spectroscopy. We describe here an experimental approach that enables the measurement of high-quality 2D-IR spectra from scattering pellets of zeolites, titania, and fumed silica in the OD-stretching region of the spectrum under flowing gas and variable temperature up to ∼500 ◦C. In addition to known scatter suppression techniques, such as phase cycling and polarization control, we demonstrate how a bright probe laser beam comparable in strength with the pump beam provides effective scatter suppression. The possible nonlinear signals arising from this approach are discussed and shown to be limited in consequence. In the intense focus of 2D-IR laser beams, a free-standing solid pellet may become elevated in temperature compared with its surroundings. The effects of steady state and transient laser heating effects on practical applications are discussed.

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Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts

Abstract

Bibliographical note

Data Availability Statement

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