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Pozzi EA, Sonntag MD, Jiang N, Chiang N, Seideman T, Hersam MC, Van Duyne RP. Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy with Picosecond Excitation. J Phys Chem Lett 2014; 5:2657-2661. [PMID: 26277959 DOI: 10.1021/jz501239z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Tip-enhanced Raman spectroscopy (TERS) provides chemical information about adsorbates with nanoscale spatial resolution, but developments are still required in order to incorporate ultrafast temporal resolution. In this Letter, we demonstrate that a reliable TER signal of rhodamine 6G (R6G) using picosecond (ps)-pulsed excitation can be obtained in ultrahigh vacuum (UHV). In contrast to our previous observation of irreversible signal loss in ambient TERS ( Klingsporn , J. M. ; Sonntag , M. D. ; Seideman , T. ; Van Duyne , R. P. J. Phys. Chem. Lett. 2014 , 5 , 106 - 110 ), we demonstrate that the UHV environment decreases irreversible signal degradation. As a complement to the TERS experiments, we examined the rate of surface-enhanced Raman (SER) signal decay under picosecond irradiation and found that it is also slowed in UHV compared to that in ambient. Signal decay kinetics suggest that the predominant mechanism responsible for signal loss in ps SERS of R6G is surface diffusion. Both diffusive and reactive phenomena can lead to pulsed excitation TER signal loss, and a UHV environment is advantageous in either scenario.
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Affiliation(s)
- Eric A Pozzi
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Matthew D Sonntag
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Nan Jiang
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Naihao Chiang
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Tamar Seideman
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Richard P Van Duyne
- †Department of Chemistry, ‡Department of Materials Science and Engineering, and §Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States
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Engelhardt K, Peukert W, Braunschweig B. Vibrational sum-frequency generation at protein modified air–water interfaces: Effects of molecular structure and surface charging. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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