Temple University

Other

Robert J Levis

Nicholas V Coppa

Elizabeth J Judge

Johanan H Odhner

John J Brady

In apparatus and methods of Raman spectroscopy in air, a target region is excited by a laser pump pulse exceeding the critical power for self-focusing in air and having a duration after self-focusing of 15 fs or less. A laser probe pulse having a duration in the range of 200 fs to 100 ps and an energy of at least 20 &#x3bc;J is directed at the excited target region. Stimulated Raman scattering from the interaction between the excited target region and the laser probe pulse is detected. The target region can be outside the spectrometer, with ambient air in between used for the self-focusing.

Filament-based stimulated Raman detection

Our invention allows for control of particle formation at the nanoscale, providing a means to control nanoparticle and nanostructure formation using feedback on the fly from nanoparticle characteristic analysis and optimization/knowledge extraction control algorithms. A closed loop feedback controller causes the interaction of a shaped flaser pulse with a substrate. The substrate can be one or more solid, liquid or gas or any combination thereof. Nanoparticles are produced and their characteristics are measured. The measured characteristics are compared with the desired nanoparticle characteristics. If the measured and desired characteristics are not equivalent, the closed loop feedback controller modifies the shape of the laser pulse and the next cycle begins. With successive loop of the control process the difference between the desired and measured characteristics converges until they are equivalent. At the end of the process a relationship is developed between the desired nanoparticle characteristics and the laser pulse shape. A catalog of all pulse shapes generated and the resulting nanoparticle characteristics is generated each time the processor is cycled whether or not the nanoparticle characteristics are those desired.

Control of particle formation at the nanoscale

Methods and apparatus for analyzing samples are disclosed. The samples are analyzed by vaporizing molecules from a sample in a sample area with a femtosecond laser beam under ambient conditions, ionizing the vaporized molecules with electrospray ionization under the ambient conditions to form ions; and analyzing and detecting the ions.

Growing community of inventors

Rose Valley, PA, United States of America

Robert J Levis