1. N.L. Tran, J.Z. Sexton, T.J. Grassman, B. Fruhberger, A.C. Kummel University of California, San Diego S.V. Patel, T.E. Mlsna Seacoast Science AFOSR MURI# F49620-02-1-0288 Test Chamber Mass Flow Control Temperature Controlled Enclosure Heat Exchanger Flow Meter Data Acquisition And Control PC 4-Way Valve Temperature Controlled Bubblers Carrier Gas Exhaust Goal Determination of Material Growth and Analyte Interaction Evaluation of Sensor Performance DFT Computation Phthalocyanine Deposition Current Capabilities: In Preparation: Develop Instruments to: (a) Fabricate Metallo-Phthalocyanine (MPC) Chemically Sensitive Field Effect Transistor (ChemFet) (b) Test MPC ChemFETs (c) Image Sensor Materials 1 3 2  E binding of Cl 2 using GGA-DFT Binding Site[eV] 1.-1.40 2.-1.05 3.-1.41 DFT simulations can aid in the assignment of observed STM features Computation suggest multiple possible binding sites for Cl 2 (Cu and the organic ligand) Custom designed MBE cell for MPc deposition MBE cell capabilities include: fast introduction of different MPcs differential pumping H 2 O cooled Cu heat shield to minimize heat transfer and protect UHV instrumentation plate valve allowing separation between MBE cell and UHV chamber Low T effusion cell Linear & Linear/Rotary feedthroughs control plate valve Cu cooling shield braised onto SS can Two mounted tees to connect shafts to feedthroughs Two side ports for mounting turbo pump and ion gauge Effusion cell shutter Plate valve Cu spacers for heat transfer – also act as hard stops Linear feedthrough Cu plate Linear/rotary feedthrough Viton o-ring for sealing Closed to UHV Open to UHV And for deposition Low Temperature STM for Single Molecule Studies: funded by NSF Scanner: Beetle type with x-,y-coarse movement Cooling: Liquid He bath cryostat; Scanner 100% surrounded by a 4K shield Vibration isolation: Internal spring system with eddy current damping and external isolation with pneumatic isolation leg Additional shutter to control in-situ gas dosing at low temperature onto STM mounted sample Temperature variation either by heating the complete STM scanner or just the sample The Createc STM-SY-014-2 combines a low-temperature STM (LT-STM) with three chambers: load-lock, sample preparation, and analysis. High Resolution Images of Complex Molecules At Low Temperature due to Extremely Stable Environment Instrument Features: - Additional He gas cooled radiation shield in between to improve the thermal isolation - Eddy current vibration damping of the pendulum motion of the inner cryostat - STM is completely isolated (thermally and electrically) when tunneling (a) 8K STM image of TBPP (porphyrin) on Cu(100), (b) STM simulation of TBPP/Cu(100); (c) structure of TBPP on Cu(100). Note the excellent submolecular resolution at the good agreement with the simulation. From Moresco et al 50 electrical feedthroughs Closed-loop temperature control: 0 - 100 ± 0.05° C; 20 minute response time Closed-loop relative humidity control: 0 - 100% ± 2% RH; 10 minute response time Open-loop permanent gas concentration control: 0 - 40000 ± 4 ppm; 4 minute response time; or, Open-loop volatile organics concentration control: up to 8 volatile organics from temperature-controlled bubblers in any one experiment, 4 minute response time Temperature and humidity sensors inside chamber Outer enclosure with closed-loop temperature control: 25 ± 0.5°C Test runs are fully automated Room temperature STM Filled state image of CuPc on Au(111) at monolayer coverage Metal center of adsorbed CuPc appears dark, consistent with unfilled Cu-dz 2 orbitals Conditions: -1 V sample bias, 0.3 nA tunneling current 60 Å x 60 Å Future Plans Plate valve mechanics: Use STM to image growth modes and analyte binding sites for Metallo-Phthalocyanines Test sensors for ppb sensitivity and selectivity to Chemical Warfare Agent (CWA) simulants