Al-Amin Dhirani

Academic Title: Associate Professor

Phone: 416-946-5789

Office: LM 254

Email:

Research Homepage: http://www.chem.utoronto.ca/staff/DHIRANI/index.htm

One branch of our research focuses on synthetic strategies, properties and potential applications of nanostructures. Such systems offer exciting opportunities: at sufficiently small length scales, the electro-optic behaviour of materials is strongly influenced by the wave nature of electrons, very much the same way that light exhibits diffraction when it interacts with small enough structures. We are particularly interested in current flow on the nanometer scale where effects such as confinement, delocalization and charging play important roles. 

Probing nanostructures can be challenging because of their small size. We use a number of techniques to facilitate our studies, including spontaneous self-assembly to prepare many copies of our systems and scan probe microscopy to investigate their properties on the nanometer scale. A major part of our research program is the advancement of both these techniques. 

We have constructued a customized, low current scanning tunneling microscope, and observed that a novel class of semiconducting organic  monolayers exhibits a high degree of spontaneous molecular ordering (see figure). Electrical measurements of the monolayers exhibited Schottky  diode-like rectification. In the short run, we would like to extend our capabilities to probe individual nanostructures down to the molecular level. In the long run, we will use scan probe methods to consider biological systems. 

We have also performed experiments involving the conception, construction and application of a new type of longitudinal atom interferometer. In these experiments, atoms were placed in a coherent superposition of momentum states, which were eventually overlapped (interfered). The interferometer was used to measure and manipulate the density matrix of an atomic beam. Experiments with deBroglie interferometers demonstrating matter wave correlations and precision measurements are currently being developed. 

• E. E. Kwan, H. Ohorodnyk, A. Orozco, I. Miller and A.-A. Dhirani, "Investigating light-matter interactions using economical laboratory built spectrometers," submitted for publication.
• P.-E. Trudeau, A. Escorcia and A.-A. Dhirani, "Variable single electron charging energies and percolation effects in molecularly linked nanoparticle films," J. Chem. Phys. in press.
• J. A. M. Dinglasan, A. Shivji and A.-A. Dhirani, "Oligoazomethine-doped planar tunnel junctions: correlating molecular structure with junction electrical characteristics," J. Chem. Phys. in press.
• Y. Suganuma and A. Dhirani, "A hybrid scanning tunneling -atomic force microscope operable in air," Rev. Sci. Instr. in press.
• Y. Suganuma, P. -E. Trudeau, B. Leathem, B. Shieh and A. Dhirani, "Discrete electron forces in a nanoparticle-tunnel junction system," J. Chem. Phys. 118 (2003) 9769 . ( Selected by editors for publication in May 26, 2003 issue of the Virtual Journal of Nanoscale Science & Technology ( http://www.vjnano.org ).)
• Y. Suganuma, P. E. Trudeau and A. Dhirani, "Probing correlated current and force effects of nanoparticle charge states by hybrid STM-AFM," Phys. Rev. B 66 (2002) 241405. ( Also  in January 1, 2003 issue of the Virtual Journal of Biological Physics Research ( http://www.vjbio.org ).   Highlighted in Research News section of Materials Today, March 2003. )