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Effect of electric field gradient on sub-nanometer spatial resolution of tip-enhanced Raman spectroscopy.

Meng L, Yang Z, Chen J, Sun M - Sci Rep (2015)

Bottom Line: However, the physical mechanism underlying is still under discussion.Here we theoretically investigate the electric field gradient of a coupled tip-substrate system.Particularly, in the case of TERS of flat-lying H₂TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report.

View Article: PubMed Central - PubMed

Affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing. 100190, China [2] Department of Physics, Xiamen University, Xiamen. 361005, China.

ABSTRACT
Tip-enhanced Raman spectroscopy (TERS) with sub-nanometer spatial resolution has been recently demonstrated experimentally. However, the physical mechanism underlying is still under discussion. Here we theoretically investigate the electric field gradient of a coupled tip-substrate system. Our calculations suggest that the ultra-high spatial resolution of TERS can be partially attributed to the electric field gradient effect owning to its tighter spatial confinement and sensitivity to the infrared (IR)-active of molecules. Particularly, in the case of TERS of flat-lying H₂TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report. Our theoretical study offers a new paradigm for understanding the mechanisms of the ultra-high spatial resolution demonstrated in tip-enhanced spectroscopy which is of importance but neglected.

No MeSH data available.


Related in: MedlinePlus

Schematics of electric field (a) and electric field gradient (b) intensity distribution of the plane between the tip and substrate in TERS configuration.
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f1: Schematics of electric field (a) and electric field gradient (b) intensity distribution of the plane between the tip and substrate in TERS configuration.

Mentions: To study in detail the electric field enhancement and the electric gradient enhancement in TERS, we perform a numerical simulation, where a model of a conical gold tip on a silver substrate is employed. The exact TERS configuration is shown in Fig. 1 where a gold tip with final radius of 2 nm and a full cone angle ϕ is placed 1 nm above a silver substrate. The tip-substrate is illuminated with a p-polarized plane wave at an angle of 60° relative to the tip, and its electric field amplitude is set at 1.0 V/m.


Effect of electric field gradient on sub-nanometer spatial resolution of tip-enhanced Raman spectroscopy.

Meng L, Yang Z, Chen J, Sun M - Sci Rep (2015)

Schematics of electric field (a) and electric field gradient (b) intensity distribution of the plane between the tip and substrate in TERS configuration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4363867&req=5

f1: Schematics of electric field (a) and electric field gradient (b) intensity distribution of the plane between the tip and substrate in TERS configuration.
Mentions: To study in detail the electric field enhancement and the electric gradient enhancement in TERS, we perform a numerical simulation, where a model of a conical gold tip on a silver substrate is employed. The exact TERS configuration is shown in Fig. 1 where a gold tip with final radius of 2 nm and a full cone angle ϕ is placed 1 nm above a silver substrate. The tip-substrate is illuminated with a p-polarized plane wave at an angle of 60° relative to the tip, and its electric field amplitude is set at 1.0 V/m.

Bottom Line: However, the physical mechanism underlying is still under discussion.Here we theoretically investigate the electric field gradient of a coupled tip-substrate system.Particularly, in the case of TERS of flat-lying H₂TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report.

View Article: PubMed Central - PubMed

Affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing. 100190, China [2] Department of Physics, Xiamen University, Xiamen. 361005, China.

ABSTRACT
Tip-enhanced Raman spectroscopy (TERS) with sub-nanometer spatial resolution has been recently demonstrated experimentally. However, the physical mechanism underlying is still under discussion. Here we theoretically investigate the electric field gradient of a coupled tip-substrate system. Our calculations suggest that the ultra-high spatial resolution of TERS can be partially attributed to the electric field gradient effect owning to its tighter spatial confinement and sensitivity to the infrared (IR)-active of molecules. Particularly, in the case of TERS of flat-lying H₂TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report. Our theoretical study offers a new paradigm for understanding the mechanisms of the ultra-high spatial resolution demonstrated in tip-enhanced spectroscopy which is of importance but neglected.

No MeSH data available.


Related in: MedlinePlus