Product Code: ICAL07_P501

Effects of Laser Parameters on Heat Distribution in a Cylindrical Sample
Authors:
Daniel Perez, Universidad de Los Andes; Bogota Colombia
Jagdish Luthra, Universidad de Los Andes; Bogota Colombia
Suranjana Luthra, The University of Alabama; Tuscaloosa AL USA
Jerald Izatt, The University of Alabama; Tuscaloosa AL USA
Alvin Winters, The University of Alabama; Tuscaloosa AL USA
Presented at ICALEO 2007

The coherence, directionality and high power in the focal area make laser sources a very convenient source for controlled heating of a sample. The distribution of heat and temperatures produced by laser heating could also be used to control the reaction rates. In this paper we investigate the effects of laser parameters like power, beam size, profile and mode structure on the heating of a cylindrical sample of dipeptide and observe the amount of hydrolysis produced. We model the heating of a solution of dipeptide by a continuous-wave CO2 laser which hydrolyzes and evaporates the solution resulting in production of amino acids. We solve the heat conduction equation for a cylindrical sample and find the distributions of temperatures and heat at the point of phase transition. We plot contours to find zones of various temperatures in the sample. Steady state conditions are assumed with no convection. Heat losses from the cylindrically boundary of the sample are included in our model. A comparison of our theoretical calculation is made with the experimental results. We investigate conditions of optimal hydrolysis versus evaporation. We vary laser power, beam size and modes of laser and consider various profiles like Gaussian, square and cosine shapes. We determine heating zones and volumes of different temperature zones heated from the surface.