Optical Probe Thermometry Using Optically Trapped Erbium Oxide Nanoparticles
- PDF / 355,395 Bytes
- 9 Pages / 432 x 648 pts Page_size
- 73 Downloads / 176 Views
Optical Probe Thermometry Using Optically Trapped Erbium Oxide Nanoparticles Samuel C. Johnson1, Susil Baral1, Arwa A. Alaulamie1, and Hugh H. Richardson1 1
Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701
ABSTRACT A new thermal imaging technique is characterized that uses an optically trapped erbium oxide nanoparticle cluster of approximately 150 nm. This technique can measure absolute temperature and has an imaging spatial resolution of the trapped particle. Scanning optical probe thermometry has been used to thermally image a cluster of gold nanowires that were excited with the trapping laser. Following a deconvolution of the measured thermal profile, a point spread function of the imaging technique has been determined to be a Gaussian with a FWHM of 165 nm. This width is a function of the clustering of Er2O3 nanoparticles used to image the nanowire. Optical probe thermometry has further been used to measure the temperature of nucleation events where a dichotomy of temperature for nucleated water occurs from degassed water and native water. Degassed water has been measured to nucleate at 555K confirming water adjacent to the gold nanoparticle superheats to the spinodal decomposition temperature before nucleating into a water vapor bubble. Following this event, the temperature inside the vapor bubble rises to the melting point of the gold nanoparticle, 1300 K which is followed by temperature stabilization. The rapid and significant temperature increase is attributed to the loss of a thermal dissipation pathway, to the surrounding water, previously available to the gold nanoparticle due to the insulator nature of the growing vapor envelope around the gold nanoparticle. INTRODUCTION Understanding heat transfer at the nanoscale is essential to design new technologies in many fields of current research but advances in prediction and manipulation of thermal energy have been hampered by a lack of control and sensitivity needed to measure thermal behavior at the meso and nanoscales.1 For example, in the semiconductor industry, as device dimensions continue to be reduced and number densities increase, heat dissipation becomes an increasingly serious problem. This problem is worsened by the fact that certain pathways for heat dissipation may become less efficient at the nanoscale because the size of the nanostructure is close in scale to the phonon mean-free path and, in this size regime, the classical heat diffusion law breaks down with current models not fully describing experimental observations.1-3 Photothermal heating of noble metal nanostructures is an active area of research,4-26 where applications have been demonstrated in many different areas including remote release of encapsulated material27, melting of strands of DNA28, thermal therapy for destruction of tumors29, and controlled manipulation of phase transitions of phospholipid membranes30. In addition to the traditional research interests in photothermal cancer therapy,29, 31-33 a new area of research has been initiated where the
Data Loading...
