Optically controlled thermal management on the nanometer length scale

Abstract

The manipulation of polymers and biological molecules or the control of chemical reactionson a nanometer scale by means of laser pulses shows great promise for applications inmodern nanotechnology, biotechnology, molecular medicine or chemistry. A controllable,parallel, highly efficient and very local heat conversion of the incident laser light intometal nanoparticles without ablation or fragmentation provides the means for atool like a ‘nanoreactor’, a ‘nanowelder’, a ‘nanocrystallizer’ or a ‘nanodesorber’.In this paper we explain theoretically and show experimentally the interaction of laserradiation with gold nanoparticles on a polymethylmethacrylate (PMMA) layer (one-photonexcitation) by means of different laser pulse lengths, wavelengths and pulse repetition rates.To the best of our knowledge this is the first report showing the possibility of highly local(in a 40 nm range) regulated heat insertion into the nanoparticle and its surroundingswithout ablation of the gold nanoparticles. In an earlier paper we showed that near-infraredfemtosecond irradiation can cut labeled DNA sequences in metaphase chromosomes belowthe diffraction-limited spot size. Now, we use gold as well as silver-enhanced goldnanoparticles on DNA (also within chromosomes) as energy coupling objects forfemtosecond laser irradiation with single-and two-photon excitation. We show the resultsof highly localized destruction effects on DNA that occur only nearby the nanoparticles.