Photothermal-reaction-assisted two-photon lithography of silver nanocrystals capped with thermally cleavable ligands

Abstract

We report an alternative approach to produce micropatterns of metallic nanoparticles using photothermal-reaction-assisted two-photon direct laser writing. The patterns are achieved using a facile surface treatment of silver nanoparticles ͑Ag NPs͒ functionalized with thermally cleavable ligands; N-͑tert-butoxycarbonyl͒-L-cysteine methyl ester. The ligand cleavage initiated by pulsed laser-induced thermal reaction results in a significant change in dispersiblility of the nanocrystals, thereby enabling a solvent-selective development process after photopatterning. We demonstrated that Ag NP patterns with submicron linewidths can be achieved using near infrared pulsed laser illumination.

Probing and Controlling Photothermal Heat Generation in Plasmonic Nanostructures

“…This emerging branch of plasmonics, deemed thermoplasmonics, focuses on designing efficient, optically-induced nanoscale heat sources [2][3][4][5] . The ability to generate point-like heat sources is not only useful for probing the fundamentals of nanoscale heat transfer, but has potential for several important applications such as medical therapy [6][7][8][9] , heat-assisted magnetic recording 10,11 , chemical catalysis [12][13][14][15] , phononic circuitry 16,17 , thermal lithography 18 , and thermophotovolatics 19,20 . This area has only recently attracted interest from researchers, yet initial results are promising.…”

Metaphotonics: An emerging field with opportunities and challenges

“…To achieve photopatterning, Kim et al 243 compound (PAG). The exposed pattern is fixed on the substrate coated with a dispersion of the nanoparticles.…”

“…238,239,240,241,242,243,244,245 It is analogous to electron-beam lithography except that the writing uses photons instead of electrons and that three-dimensional structures can be made in a single lithography step ( Figure 14). To do this, a laser is tightly focused into the volume of an essentially transparent photoresist.…”

Coupled plasmons induce broadband circular dichroism in patternable films of silver nanoparticles with chiral ligands

“…26. 26 The t-BOC protected ligand is readily activated and deprotected photothermally, driven by nonlinear (two-photon) LSPR absorption. Several groups have recently utilized two-photon lithography for the patterning of solid state lms by in situ growth of MNPs in a polymer matrix.…”

“…[27][28][29][30] However, this approach results in limited loading of MNPs in the patterned area. 26 Briey, under femtosecond pulsed laser irradiation at 800 nm, the silver nanoparticles in the lm are excited through two-photon absorption, which is particularly strong because the LSPR frequency of the silver nanoparticles ($400 nm) is matched to two 800 nm photons. The MNPs may lose their individual properties (e.g.…”