Nanosecond Photothermal Effects in Plasmonic Nanostructures

Abstract

Photothermal effects in plasmonic nanostructures have great potentials in applications for photothermal cancer therapy, optical storage, thermo-photovoltaics, etc. However, the transient temperature behavior of a nanoscale material system during an ultrafast photothermal process has rarely been accurately investigated. Here a heat transfer model is constructed to investigate the temporal and spatial variation of temperature in plasmonic gold nanostructures. First, as a benchmark scenario, we study the light-induced heating of a gold nanosphere in water and calculate the relaxation time of the nanosphere excited by a modulated light. Second, we investigate heating and reshaping of gold nanoparticles in a more complex metamaterial absorber structure induced by a nanosecond pulsed light. The model shows that the temperature of the gold nanoparticles can be raised from room temperature to >795 K in just a few nanoseconds with a low light luminance, owing to enhanced light absorption through strong plasmonic resonance. Such quantitative predication of temperature change, which is otherwise formidable to measure experimentally, can serve as an excellent guideline for designing devices for ultrafast photothermal applications.

Near‐Infrared‐Plasmonic Energy Upconversion in a Nonmetallic Heterostructure for Efficient H2 Evolution from Ammonia Borane

“…However, in our case, the NaYF 4 NPs are directly in contact with the plasmonic W 18 O 49 NWs and the nonradiative energy transfer to W 18 O 49 NWs provides an efficient decay channel to quench the upconversion luminescence 31, 32, 33, 34. The time‐resolved luminescence spectroscopy indicated that the lifetimes of 2 I 11/2 → 4 I 15/2 (521 nm), 4 S 3/2 → 4 I 15/2 (545 nm), and 4 F 9/2 – 4 I 15/2 (660 nm) decays for the NaYF 4 :Yb‐Er/W 18 O 49 film were shorter than the corresponding lifetimes obtained from the individual NaYF 4 :Yb‐Er film (Figure S7, Supporting Information).…”

“…Meanwhile, the LSPR‐enhanced localized electric field can interact with the emission electric field of NaYF 4 :Yb‐Er NPs to boost the radiative decay rate of upconversion process 4, 7. However, the direct contact of W 18 O 49 NWs and NaYF 4 :Yb‐Er NPs quenches the upconversion emission to a certain degree due to the nonradiative energy transfer from the NaYF 4 :Yb‐Er NPs (donor) and the adherent W 18 O 49 NWs (acceptor) 31, 32, 33, 34. Moreover, the upconversion luminescence of NaYF 4 :Yb‐Er NPs can also be absorbed by the adjacent W 18 O 49 NWs, which selectively weakens the luminescence intensity depending on the absorption band of W 18 O 49 NWs.…”

“…The radiative rate enhancement is originated from the plasmon‐enhanced emission field, while the nonradiative process in the NaYF 4 :Yb‐Er/W 18 O 49 film is mainly attributed to the mentioned energy transfer. This nonradiative energy transfer is strongly dependent on the distance between luminescent centers and plasmonic nanostructures 33, 34. For NaYF 4 :Yb‐Er NPs, the luminescent centers of Er 3+ ions are uniformly dispersed in the insulating NaYF 4 host 30.…”

“…Photothermal effect: After LSPR excitation by 980 nm, the W 18 O 49 NWs can create a super‐high temperature surrounding their surfaces (similar to the noble metal nanostructures),34, 35 which would influence the upconversion luminescence of the neighboring NaYF 4 :Yb‐Er NPs in the composite film. It is well known that in the case of NaYF 4 :Yb‐Er, the energy separation (≈840 cm −1 ) between 2 H 11/2 and 4 S 3/2 levels can allow the thermally excited population from the 4 S 3/2 to 2 H 11/2 level, and a quasi‐thermal equilibrium forms between these two levels, resulting in the variation in the transitions of 2 I 11/2 → 4 I 15/2 (521 nm) and 4 S 3/2 → 4 I 15/2 (545 nm) at an increased temperature (Equation (S21), Supporting Information) 36, 37, 38.…”

Laser-matter interactions, phase changes and diffusion phenomena during laser annealing of plasmonic AlN:Ag templates and their applications in optical encoding

“…1 The LSPR traits are strong light absorption, scattering and light field focusing on the NP surface, and are the keystone of the emerging field of plasmonics [2][3][4][5][6][7][8][9][10][11][12] which promises radical breakthroughs in optical storage and transport of information. Strong intensity laser light, on the other hand, interacts with the metal NPs in many more complex ways, which include the self assembly of particles from individual metal atoms, 13 particle reshaping, [14][15][16][17][18][19][20] melting and recrystallization, 21-25 metal growth, 26 and even structural alteration of the dielectric matrix. 27 This photosensitivity is a property of the composite metallodielectric system and depends on the fine details of both the initial NP/host structure and the laser source.…”