CPAC Gets New Home

The Department of Chemistry has been home to the Center for Process Analytical Chemistry since its founding in 1984. The original focus of the center was the development of fundamental chemometric methods to analyze industrial processes. During the intervening nearly three decades, CPAC has evolved considerably, embracing new challenges as they have emerged in industrial process analysis and control. The original focus within the Department of Chemistry at the University of Washington has broadened considerably. Today’s CPAC is a multi-university, multi-disciplinary organization, with an increasing focus on applied research. Interim Vice Provost David Eaton, together with Chemistry Chair Paul Hopkins and CPAC Faculty Director Robert Synovec, recently wrote to CPAC’s 30 industrial sponsors to indicate that, “After a thorough assessment of the organizational and financial structure of CPAC, we have concluded that CPAC warrants a new administrative home that better reflects both the applied nature of CPAC research and its expanding scope in industrial processes and controls.” Effective March 17, 2011 CPAC moved to the UW Applied Physics Laboratory. The industrial members have been asked to affirm a new name that retains the CPAC acronym, but that better reflects the current breadth of its activites, the “Center for Process Analysis and Control”. Additionally, Professor and Associate Chair Robert Synovec of the Department of Chemistry, who has served as Faculty Director of CPAC since 2007, has handed over the postion of CPAC Director to Dr. Bryan Marquardt, Senior Engineer in the Applied Physics Laboratory, and Affiliate Assistant Professor of Electrical Engineering. The Department of Chemistry thanks Professor and Associate Chair Synovec for his service to CPAC, and wishes CPAC well in its new home!

Jen et al. describe nanoscale molecular control in Science

Professor Alex Jen, Boeing-Johnson Chair professor of materials science and engineering and professor of chemistry, and his co-workers have demonstrated the ability to foster an extremely unlikely chemical reaction between two molecules by tethering them into the correct orientation on a gold surface. The study is reported in the March 11, 2011 issue of Science. The research was also highlighted in the March 14, 2011 issue of Chemical & Engineering News:

“In the work, chemists led by Paul S. Weiss and Kendall N. Houk of the University of California, Los Angeles, and Alex K-Y. Jen of the University of Washington, Seattle, tied two anthracene analogs next to each other on a gold surface. This forced the molecules to react in a manner that, although theoretically possible in solution, rarely occurs there because of unfavorable geometry.

“In principle, the mallet-shaped molecule 9-phenylethynylanthracene (PEA) should undergo a 4 + 4 photocycloaddition with another molecule of PEA. But because of geometric constraints, that reaction rarely happens. Instead, one PEA’s anthracene moiety tends to do Diels-Alder chemistry with the ethynyl unit on another PEA’s phenylethynyl handle.

“To force the disfavored reaction, the researchers attach a thiol group to the end of PEA’s handle and tether two such molecules next to one another on a gold surface within the defect sites of a self-assembled alkanethiolate monolayer. The anthracene moieties are then poised in the correct orientation to do the photocycloaddition when photoexcited.”

To learn more about Prof. Jen’s research, visit his group research page.

For more information about the Science article, read the UW press release.

Spinning Quantum Dots reported in Nature Nanotechnology

Dr. Stefan Ochsenbein, a postdoc working with Prof. Daniel Gamelin, Harry and Catherine Jaynne Boand Endowed Professor of Chemistry, is lead author on a new paper published in Nature Nanotechnology reporting the first successful coherent impurity spin manipulation within colloidal semiconductor nanocrystals (also known as quantum dots). Spin effects in semiconductor nanostructures have attracted broad interest for potential spin-based information processing technologies, whether in spin-electronics (“spintronics”) or spin-photonics. Colloidal doped semiconductor nanocrystals present interesting possibilities for constructing devices by solution processing or that involve integration with soft materials (e.g., organics), but their spin properties remain relatively untested. For example, the possibility to manipulate spins within colloidal semiconductor nanocrystals coherently, as would be necessary for many proposed applications, had not been demonstrated until these latest experiments.

In this paper, Ochsenbein and Gamelin describe the first observation of coherent spin manipulation in colloidal doped quantum dots. The observation was made by demonstrating microwave-driven Rabi oscillations within the high-spin ground states of Mn2+ impurity ions doped into colloidal ZnO semiconductor nanocrystals. Their electron spin-echo measurements revealed long spin coherence times approaching 1 µs, sufficient for potential qubit applications with optical excitation. The authors also identified previously unobserved hyperfine interactions between Mn2+ electron spins within the quantum dots and proton nuclear spins outside the quantum dots, revealing an important but previously unrecognized contribution to spin decoherence in such quantum dots.

Read the article: “Quantum oscillations in magnetically doped colloidal nanocrystals.” Ochsenbein, S. T.; Gamelin, D. R., Nature Nanotechnology, 2011, 6, 112–115.

To learn more about Prof. Gamelin’s research, visit his faculty webpage and research group website.