LSM - Seminars: September 2009 Archives

Seminars Archives

May 2009 | September 2009 | October 2009

Thursday, September 10, 2009
Novel type of nanoscale modification of organic semiconductors: self-assembled monolayers at organic surfaces Vitaly Podzorov. Rutgers Physics 12:00 PM, Chem. 260 It was discovered that self-assembled monolayers (SAM) of silanes could be grown directly at the surface of small-molecule [1] and polymer [2] organic semiconductors, the materials of a great interest for organic electronics. One of the most interesting consequences of SAM formation on these materials is a high-density 2D hole gas induced at the SAM-organic interface [1,2]. This talk will cover our basic observations and other interesting effects related to this phenomenon. It will also include a discussion of surface characterization of pristine and SAM-modified molecular crystals and conjugated polymers, providing insights into the SAM composition and growth mechanism. Novel transport and optical properties of SAM-functionalized organic semiconductors will be briefly discussed [3]. 1. M. F. Calhoun et al., "Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers", Nature Mat. 7, 84 (2008). 2. C.-Y. Kao et al, "Doping of conjugated polythiophenes with alkyl silanes", Adv. Funct. Mater. 19, 1 (2009). 3. B. Lee et al., to appear in Adv. Funct. Mater. (2009).

Thursday, September 10, 2009

Novel type of nanoscale modification of organic semiconductors: self-assembled monolayers at organic surfaces
Vitaly Podzorov. Rutgers Physics
12:00 PM, Chem. 260

It was discovered that self-assembled monolayers (SAM) of silanes could be grown directly at the surface of small-molecule [1] and polymer [2] organic semiconductors, the materials of a great interest for organic electronics. One of the most interesting consequences of SAM formation on these materials is a high-density 2D hole gas induced at the SAM-organic interface [1,2]. This talk will cover our basic observations and other interesting effects related to this phenomenon. It will also include a discussion of surface characterization of pristine and SAM-modified molecular crystals and conjugated polymers, providing insights into the SAM composition and growth mechanism. Novel transport and optical properties of SAM-functionalized organic semiconductors will be briefly discussed [3].

1. M. F. Calhoun et al., "Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers", Nature Mat. 7, 84 (2008).
2. C.-Y. Kao et al, "Doping of conjugated polythiophenes with alkyl silanes", Adv. Funct. Mater. 19, 1 (2009).
3. B. Lee et al., to appear in Adv. Funct. Mater. (2009).

Thursday, September 24, 2009
Up Against the Wall: Liquid Lithium for the Chamber Technology Challenge in Fusion Robert Kaita, Princeton Plasma Physics Lab 12:00 PM, Chem. 260 For both inertial and confinement fusion, a critical need is to develop an appropriate "first wall" that will face thermonuclear plasmas. It has been difficult to find a solid material for the high power densities and large neutron fluxes that a plasma-facing component (PFC) must handle for long periods of time. An alternative is to use liquid metals for a fusion reactor PFC. Radiation damage will not be an issue for such PFCs, and since they can flow, they are able to dissipate high heat loads. Furthermore, any material removed by erosion can be readily replenished. At the Princeton Plasma Physics Laboratory (PPPL), there is an active program in small and large-scale magnetic confinement devices to develop a liquid lithium PFC. To simulate high power loads, experiments were conducted with an electron beam directed at a large, free-surface liquid lithium "pool," and effective heat dissipation through convective cooling was demonstrated. Discharges with lithium as a PFC showed a marked reduction in recycling, or the re-introduction of cold fuel gas into the plasma from the chamber wall, and a significant improvement of energy confinement was observed. This talk will describe lithium PFC research on two facilities at PPPL. The Lithium Tokamak Experiment (LTX) is a modest sized toroidal confinement device that is the first to have a conformal liquid lithium wall that encloses the plasma. The National Spherical Torus Experiment (NSTX) is a larger magnetic fusion machine that is the first to have liquid lithium in its divertor region. Host: Robert Bartynski

Thursday, September 24, 2009

Up Against the Wall: Liquid Lithium for the Chamber Technology Challenge in Fusion
Robert Kaita, Princeton Plasma Physics Lab
12:00 PM, Chem. 260

For both inertial and confinement fusion, a critical need is to develop an appropriate "first wall" that will face thermonuclear plasmas. It has been difficult to find a solid material for the high power densities and large neutron fluxes that a plasma-facing component (PFC) must handle for long periods of time. An alternative is to use liquid metals for a fusion reactor PFC. Radiation damage will not be an issue for such PFCs, and since they can flow, they are able to dissipate high heat loads. Furthermore, any material removed by erosion can be readily replenished. At the Princeton Plasma Physics Laboratory (PPPL), there is an active program in small and large-scale magnetic confinement devices to develop a liquid lithium PFC. To simulate high power loads, experiments were conducted with an electron beam directed at a large, free-surface liquid lithium "pool," and effective heat dissipation through convective cooling was demonstrated. Discharges with lithium as a PFC showed a marked reduction in recycling, or the re-introduction of cold fuel gas into the plasma from the chamber wall, and a significant improvement of energy confinement was observed. This talk will describe lithium PFC research on two facilities at PPPL. The Lithium Tokamak Experiment (LTX) is a modest sized toroidal confinement device that is the first to have a conformal liquid lithium wall that encloses the plasma. The National Spherical Torus Experiment (NSTX) is a larger magnetic fusion machine that is the first to have liquid lithium in its divertor region.

Host: Robert Bartynski

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