N.L. Tran , J.Z. Sexton, T.J. Grassman, B. Fruhberger, A.C. Kummel
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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 depositi on 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 LHe dewar (4 l) shutter for sample & tip transfer radiation shields (LN 2 , LHe) eddy current damping for the LHe cryostat STM head He gas cooled radiation shield linear feedtrough 4” (to pull down the STM) rotary feedtrough (transfer shutter) electrical feedtroughs STM-contacts (37-pin plug) Cabling (stainless steel) baffles LN 2 dewar (14 l) • 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
description
Data Acquisition And Control PC. Mass Flow Control. Exhaust. Temperature Controlled Enclosure. Test Chamber. Heat Exchanger. Flow Meter. 4-Way Valve. Temperature Controlled Bubblers. Carrier Gas. 1. 2. 3. rotary feedtrough (transfer shutter). electrical feedtroughs. Cabling - PowerPoint PPT Presentation
Transcript of N.L. Tran , J.Z. Sexton, T.J. Grassman, B. Fruhberger, A.C. Kummel
N.L. Tran, J.Z. Sexton, T.J. Grassman, B. Fruhberger, A.C. Kummel
University of California, San DiegoS.V. Patel, T.E. Mlsna
Seacoast Science AFOSR MURI# F49620-02-1-0288
TestChamber
Mass Flow Control
Temperature ControlledEnclosure
HeatExchanger Flow
Meter
Data AcquisitionAnd Control PC
4-WayValve
TemperatureControlled BubblersCarrier
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
Ebinding of Cl2 using GGA-DFT
Binding Site [eV]1. -1.402. -1.053. -1.41
DFT simulations can aid in the assignment of observed STM features
Computation suggest multiple possible binding sites for Cl2 (Cu and the organic ligand)
• Custom designed MBE cell for MPc deposition
• MBE cell capabilities include:• fast introduction of different MPcs• differential pumping• H2O 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 shieldbraised 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
Closedto UHV
Opento UHVAnd 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 inbetween to improve the thermal isolation
- Eddy current vibration damping of thependulum motion of the inner cryostat
- STM is completely isolated (thermally andelectrically) 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
LHe dewar(4 l)
shutter for sample& tip transfer
radiation shields(LN2, LHe)
eddy current dampingfor the LHe cryostat
STM head
He gas cooledradiation shield
linear feedtrough 4”(to pull down the STM)
rotary feedtrough(transfer shutter)
electrical feedtroughs
STM-contacts(37-pin plug)
Cabling(stainless steel)
baffles
LN2 dewar(14 l)
• 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-dz2 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
