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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: 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.

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.


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: 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.

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.