Enhanced Raman scattering for temperature measurement of a laser-heated atomic force microscope tip

Abstract

Illuminating a silicon cantilever of an atomic force microscope with a focused laser beam creates heat that can be funneled into a nanoscale area at the apex of its tip. To characterize the heating dynamics and measure the temperature of the tip, a Raman scattering pump-and-probe method is used. It is found that at the apex of the tip the intensity of the Raman Stokes and anti-Stokes components are significantly enhanced relative to those obtained on a bulk silicon sample. Modeling the temperature rise at the tip of the cantilever by a closed-form analytical expression gives good agreement with the Raman measurements. This model can be used to design the structure of the cantilever so that the heat delivery to its tip is optimized. Such an optimized cantilever can potentially be used in high-density, heat-assisted magnetic recording, optical data storage using phase-change media and thermomechanical recording systems, for example, where nanoscale heated regions are of importance.

Scanning thermal lithography for nanopatterning of polymers

“…The relatively high error value is ascribed to the use of polymer melting point standard materials for the probe tip temperature calibration (see Chapter 2). The calculated T m app value of the semi-crystalline PFS core is in good agreement with the melting temperature range of PFS in bulk PI 76 -b-PFS 76 samples measured with DSC. We note that NanoTA uses typically high temperature ramp rates (~ 10 °C s -1 ).…”

“…The observed rapid recrystallization was explained by the presence of a high number of nuclei still present up to the equilibrium melting temperature of PFS 76 is not completely irreversible as is observed from the presence of a type I melting endotherm in the second heating trace. This is ascribed to the restricted chain mobility in the confined phase separated morphology, reducing the formation of thicker lamella.…”

“…Laser heating of AFM tips was later on mainly reported for the spatially controlled nanopatterning of surfaces 73,74 as well as for the development of heated tip temperature characterization methods (See Section 2.4). 75,76 The required second external laser for cantilever tip heating as well as the alignment of this laser on the probe tip, resulted in an impractical approach for their implementation in large scale applications. Hence, it was recognized that the use of probes with internal microscale heaters would greatly simplify the operating procedure.…”

“…In addition, the introduction of NanoTA as an enabling nanotechnology tool for thermal analysis of nanometer sized architectures is discussed in detail taking the results described in Chapters 3 and 4 into account. 76 Crystallization and melting behavior of PI 76 -b-PFS 76 bulk samples was first investigated with DSC. 40,41 as well as by Rehahn and coworkers for PFS homopolymers.…”

“…Drop casting of PI 76 -b-PFS 76 at SiO 2 resulted in the formation of over micrometer thick aggregates of crystals piled up on top of each other. NanoTA runs on these aggregates were successful.…”