title: Nanoscale probing of thermal, stress, and optical fields under near-field laser heating.
abstract: Micro/nanoparticle induced near-field laser ultra-focusing and heating has been widely used in laser-assisted nanopatterning and nanolithography to pattern nanoscale features on a large-area substrate. Knowledge of the temperature and stress in the nanoscale near-field heating region is critical for process control and optimization. At present, probing of the nanoscale temperature, stress, and optical fields remains a great challenge since the heating area is very small (~100 nm or less) and not immediately accessible for sensing. In this work, we report the first experimental study on nanoscale mapping of particle-induced thermal, stress, and optical fields by using a single laser for both near-field excitation and Raman probing. The mapping results based on Raman intensity variation, wavenumber shift, and linewidth broadening all give consistent conjugated thermal, stress, and near-field focusing effects at a 20 nm resolution (<λ/26, λ = 32 nm). Nanoscale mapping of near-field effects of particles from 1210 down to 160 nm demonstrates the strong capacity of such a technique. By developing a new strategy for physical analysis, we have de-conjugated the effects of temperature, stress, and near-field focusing from the Raman mapping. The temperature rise and stress in the nanoscale heating region is evaluated at different energy levels. High-fidelity electromagnetic and temperature field simulation is conducted to accurately interpret the experimental results.
authors.affiliation: Department of Mechanical Engineering, Iowa State University, Ames, Iowa, USA.
authors.forename: Xiaoduan
authors.initials: X
authors.lastname: Tang
authors.forename: Shen
authors.initials: S
authors.lastname: Xu
authors.forename: Xinwei
authors.initials: X
authors.lastname: Wang
mesh_terms: D006358:Hot Temperature; D007834:Lasers; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide
references.citation: Nat Commun. 2011;2:218
references.pmid: 21364557
references.citation: Science. 2006 Sep 15;313(5793):1595
references.pmid: 16973871
references.citation: Science. 2007 Mar 23;315(5819):1686
references.pmid: 17379801
references.citation: Rev Sci Instrum. 2008 Jul;79(7):073708
references.pmid: 18681709
references.citation: Nat Commun. 2010;1:143
references.pmid: 21266993
references.citation: ACS Nano. 2011 Jun 28;5(6):4466-75
references.pmid: 21557563
references.citation: Opt Express. 2012 Jun 18;20(13):14152-67
references.pmid: 22714479
references.citation: Nano Lett. 2007 Feb;7(2):403-8
references.pmid: 17298007
references.citation: Science. 2007 Mar 23;315(5819):1699-701
references.pmid: 17379804
references.citation: Nat Methods. 2006 Oct;3(10):793-5
references.pmid: 16896339
references.citation: Small. 2011 Dec 2;7(23):3324-33
references.pmid: 21997970
references.citation: J Microsc. 2001 Apr;202(Pt 1):129-35
references.pmid: 11298882
references.citation: Rev Sci Instrum. 2007 Jun;78(6):061301
references.pmid: 17614598
references.citation: Nat Nanotechnol. 2012 Jan 22;7(3):151-5
references.pmid: 22266635
references.citation: Nat Nanotechnol. 2008 Jul;3(7):413-7
references.pmid: 18654565
references.citation: Science. 1995 Aug 25;269(5227):1083-5
references.pmid: 17755529