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Surface-enhanced, multi-dimensional attenuated total reflectance spectroscopy


Kraack, Jan Philip; Lotti, Davide; Hamm, Peter (2015). Surface-enhanced, multi-dimensional attenuated total reflectance spectroscopy. In: Physical Chemistry of Interfaces and Nanomaterials XIV, San Diego, California, United States, 9 August 2015 - 9 August 2015.

Abstract

Ultrafast two-dimensional infrared spectroscopy (2D IR) spectroscopy is performed in attenuated total reflectance (ATR) geometry with the Kretschmann configuration in order to measure femtosecond to picosecond dynamics of selfassembled monolayers on gold-coated solid-liquid interfaces. In the monolayers low-absorbing (<200 M-1 cm-1) nitrile functional groups are used as local vibrational probes to monitor vibrational relaxation and spectral diffusion in dependence of different environments of the nitrile group. By comparing spectral diffusion dynamics of the vibrational probe in bulk solution and in the monolayer we find that the dynamics are slowed down by more than a factor of 20 upon immobilization of the sample. Moreover, spectral diffusion dynamics are affected by the local environment within the monolayers as evidenced by 2D ATR IR experiments on mixed monolayers with different aliphatic and aromatic coadsorbates. The results are interpreted in terms of absent excitation energy-transfer as well as solvation dynamics around the nitrile vibrational probe. Our results demonstrate that 2D ATR IR spectroscopy offers the possibility to obtain ultrafast dynamics from sub-monolayer coverages of even low-absorbing vibrational probes such as nitrile functional groups.

Abstract

Ultrafast two-dimensional infrared spectroscopy (2D IR) spectroscopy is performed in attenuated total reflectance (ATR) geometry with the Kretschmann configuration in order to measure femtosecond to picosecond dynamics of selfassembled monolayers on gold-coated solid-liquid interfaces. In the monolayers low-absorbing (<200 M-1 cm-1) nitrile functional groups are used as local vibrational probes to monitor vibrational relaxation and spectral diffusion in dependence of different environments of the nitrile group. By comparing spectral diffusion dynamics of the vibrational probe in bulk solution and in the monolayer we find that the dynamics are slowed down by more than a factor of 20 upon immobilization of the sample. Moreover, spectral diffusion dynamics are affected by the local environment within the monolayers as evidenced by 2D ATR IR experiments on mixed monolayers with different aliphatic and aromatic coadsorbates. The results are interpreted in terms of absent excitation energy-transfer as well as solvation dynamics around the nitrile vibrational probe. Our results demonstrate that 2D ATR IR spectroscopy offers the possibility to obtain ultrafast dynamics from sub-monolayer coverages of even low-absorbing vibrational probes such as nitrile functional groups.

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Additional indexing

Item Type:Conference or Workshop Item (Paper), refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Event End Date:9 August 2015
Deposited On:09 Dec 2015 15:25
Last Modified:08 Dec 2017 15:36
Publisher:SPIE - International Society for Optical Engineering
Series Name:Proceedings of SPIE
ISSN:0277-786X
Funders:Swiss National Foundation, University Research Priority Program (URPP) for solar light to chemical energy conversion (LightChEC)
Publisher DOI:https://doi.org/10.1117/12.2185533

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