Experimental Innovations in Surface Science (eBook)

Preface to the Second Edition 5
Preface to the First Edition 6
Contents 8
Part IVacuum System Technology 21
1 Motion in Vacuum 22
1.1 Crystal Manipulator with Six Degrees of Motional Freedom 22
1.2 Rotation in Ultrahigh Vacuum 25
1.3 Crystal Positioning Using Capacitance 30
1.4 UHV Rotary Manipulator with Arcsec Resolution 32
1.5 Solenoid Driven Linear Motion Device 34
1.6 An Inexpensive Linear Motion Device 34
1.7 Translating Auger Spectrometer 35
1.8 Simple Multiple Motion Manipulator 37
1.9 Simple Device for Small Rotations in Ultrahigh Vacuum---Grating Application 37
1.10 Turntable Rotation in Ultrahigh Vacuum 39
1.11 Small Motions in UHV Systems Using Shape Memory Effect Alloys 39
1.12 Rotary Shutter Device Driven by Magnetic Eddy Current 41
1.13 High-Speed Ultrahigh Vacuum Motor 43
1.14 High-Speed Rotary Feedthrough for UHV Operation 44
1.15 Self-lubricating Bearings in UHV 45
1.16 Lubrication for Heavy Sliding Loads in Ultrahigh Vacuum 46
1.17 Simple UHV Bearing for High-Speed Shafts 48
1.18 Flange-Mounted UHV Variable Aperture 49
1.19 Linear Motion Platform (LMP) 50
1.20 Vacuum Trolley Transport System 52
1.21 Thermally Compensated STM with Repeatable Sample Positioning 53
References 55
2 Sample Transfer 58
2.1 Sample Transfer from High Pressure to Ultrahigh Vacuum 58
2.2 Novel Sample Transfer from UHV Chamber to External Cell 64
2.3 UHV Sample Transfer Device with Low-Temperature Capability 64
2.4 Internal Cup High-Pressure Cell 68
2.5 High-Pressure Transfer Cell 69
2.6 Sample Transfer with Disconnect-I 71
2.6.1 Transfer in Standard UHV Systems 71
2.6.2 Transfer in STM Systems 73
2.7 Sample Transfer with Disconnect-II 73
2.8 Vibration-Free Translatable Device 74
2.9 Mirror Port for Enhanced Sample Transfer 75
2.10 UHV Access Port 75
References 77
3 Electrical Connections 79
3.1 Tungsten Ribbon---Attachment to Power Leads 79
3.2 Wrap Connection---Tungsten to Tungsten 80
3.3 Cold-Formed Wire Connector 82
3.4 Ultrahigh Resistance Vacuum Feedthroughs 82
3.5 Sliding Metal Electrical Contact 84
3.6 Low-Profile Electrical Lead Clamp 85
References 86
4 Pumping and Trapping 87
4.1 Water Aspirator/Sorption Pump Combination for Efficient UHV System Evacuation 87
4.2 Ballast Pumping---Vibration Free 89
4.3 The Use of Appendage Titanium Sublimation Pumps for Pumping Low Gas Loads in Ultrahigh Vacuum 90
4.4 Pressure-Equalizing Device in Complex Systems 90
4.5 Diode Ion Pump Performance in He Pumping 93
4.6 Vacuum Applications of Metal Foams 93
4.7 Cleaning of Ion Pumps by Chemical Etching 96
4.8 An Efficient Liquid Nitrogen Trap 97
References 98
5 Bakeout 100
5.1 Bakeout of Metal Ultrahigh Vacuum Systems 100
References 102
6 Behavior of UHV Systems 103
6.1 Wall Passivation in Stainless Steel Ultrahigh Vacuum Systems 103
6.2 Minimizing Wall Reactions in Ultrahigh Vacuum Systems---Gas Dosers 105
References 107
7 Mechanical Action on Samples 108
7.1 Simple UHV Crystal Cleaver 108
7.2 Piezoelectric Fatigue Apparatus for UHV Operation 110
References 112
8 Gasket Seals 113
8.1 Gasket Seals for Ultrahigh Vacuum Systems 113
8.2 Cryogenic Gasket Seals 115
8.3 Copper Gasket Removal Devices 116
8.4 Unconventional Compression Seals for Ultrahigh Vacuum 117
References 119
9 Leak Repairs and Detection 120
9.1 Coaxial Pumped He Leak Detection Probe 120
9.2 Temporary Leak Sealing of Welded Bellows 121
9.3 Atmospheric Permeation---Viton O-Ring 121
References 123
10 Specialized UHV Systems 125
10.1 Aluminum Ultrahigh Vacuum System 125
10.2 Surface Electrochemistry Apparatus 126
References 128
Part IIMechanical Fabrication Techniques 129
11 Grids 130
11.1 Hemispherical Grids---Formation and Piercing 130
11.2 Making Flat Mesh Grids of Large Size 131
11.3 Grid Fabrication Techniques---Conical Grid 132
References 133
12 Conductive Coatings 134
12.1 Deposition of Electrically Conductive SnO2 Films 134
References 136
13 Phosphor Screens 137
13.1 Sedimentation Method for Depositing Phosphor Screens 137
13.2 Dusting Method for Coating Phosphor Screens 139
References 141
14 Thermionic Emitters 142
14.1 Thoriated Thermionic Emitters 142
14.2 Lanthanum Hexaboride Thermionic Emitters---Deposition on Metals 144
14.3 Directly Heated Lanthanum Hexaboride Thermionic Emitters 146
14.4 Thermionic Emitter Mounting 148
14.5 Indirectly Heated Cathodes for High-Temperature Operation 150
14.6 Filament Power Supply Tester 150
14.7 Bayard-Alpert Ionization Gauge with Corrections for External Radiation and External Electron Flux Effects 151
14.8 Replacing Filaments in Glass Bayard-Alpert Gauges 154
References 155
15 Shielding 157
15.1 Magnetic Shielding in Ultrahigh Vacuum 157
15.2 Electrical Isolation of UHV Components 159
References 160
16 Single Crystal Fabrication/Orientation 162
16.1 Making Small Au Single Crystals from Au Wire for STM and Other Studies 162
16.2 Single Crystal Orientation, Grinding, and Polishing 163
16.3 A Simple Goniometer for Cutting Single Crystals 166
16.4 Ion Beam Polishing of Crystals to Subnanometer Roughness 167
16.5 Crystal Optical Alignment 168
16.6 Measurement of the Angles of Incidence in a LEED Experiment 169
16.7 Measurement of Angle of Incidence of an Electron Beam on a Single Crystal 170
References 172
17 Tip Fabrication 174
17.1 Fabrication of Metal Tips Using Zone Electropolishing 174
17.2 Etching STM Tips Reproducibly 175
17.3 STM Tip Flasher 177
17.4 Reverse Bias Method for Sharp Tip Etching 177
17.5 Sharpening Single Crystal Metal Tips by Ion Bombardment 180
References 181
18 Spot-Welding 182
18.1 Spot-Welding Difficult Junctions 182
References 184
19 Mechanical Procedures 185
19.1 Stretching Thin Metal Foils to a Wrinkle-Free Condition 185
19.2 Making Micron-Size Holes for Supersonic Nozzles 186
19.2.1 Method I---Fig. 19.2a 186
19.2.2 Method II---Fig. 19.2b 188
19.3 Straightening and Braiding Wires 189
References 189
Part IIIMeasurement Methods 190
20 Electrons 191
20.1 Electron Gun Design and Behavior 191
20.2 Low-Energy Electron Gun for Broad-Beam Irradiation 193
20.3 Low-Energy Electron Gun for Broad-Beam Irradiation---Cylindrical Symmetry 194
20.4 Electron Energy Analyzers 195
20.5 Electron Spectrometer Calibration Using Graphite 200
20.6 Measurement of Electron Beam Angular Divergence 202
20.7 Measuring Anisotropy of Electrical Conductivity of a Single Crystal---Four Point Probe 204
20.8 Spot Photometer for LEED Intensity Measurements 205
20.9 Modified Faraday Cup for Electron Current Measurement 206
20.10 HREELS-Discrimination Between Single and Multiple Electron Scattering Events 209
20.11 Rejuvenation of Cu/Be Electron Multipliers 209
20.12 Geiger-Müller Counter for Inverse Photoemission 210
References 212
21 Ions 214
21.1 Ion Sputter Gun with Low Gas Emission 214
21.2 Alternate Ion Bombardment Sources 216
21.3 Ion Gun Based on Bayard-Alpert Gauge 217
21.4 Sputter Ion Gun---Cold Cathode 219
21.5 Broad Ion Sources---Improved Stability with Oxygen 221
21.6 Focusing of Low-Energy Ions by Magnetic Field 223
21.7 Low Energy Ion Gun---Construction and Performance 223
21.8 Measuring Ion Beam Dimensions 226
21.9 Beam Position Monitor---Charged Particles 227
21.10 Pulse-Counting LEED/ESDIAD Analyzer---Using MicroChannel Plate Detection 228
21.11 Time-of-Flight Measurements for Ions Generated in ESDIAD 230
21.12 Ion Detection with Kinetic Energy and Mass Resolution Using a Hemispherical Energy Analyzer 232
21.13 Time-of-Flight Detection for Laser-Ionized Neutrals 234
References 235
22 Photons (UV) 238
22.1 Hollow Cathode Resonance Lamp for He(II) (40.8 eV) Photoemission 238
22.2 He(I) and He(II) Ultraviolet Resonance Source 239
22.3 Photochemistry on Surfaces Using an Ultraviolet Lamp 241
22.4 Use of Polarized Ultraviolet Light for Photochemistry 243
22.5 Photoreduction of Ag on Doped TiO2---Making Enhanced Photoactivity Visible 245
22.6 Reducing Radiation Damage in Raman Spectroscopy of Solids 246
22.7 Lyman- alpha Lamp Calibration Using a Chemical Actinometer 248
22.8 Pulsed Vacuum UV Light Source 250
22.9 Grazing Incidence X-Ray Photoemission Spectroscopy (GIXPS): Enhanced Surface Sensitivity 250
References 253
23 Kinetics of Adsorption/Adsorbate Coverages 255
23.1 Absolute Adsorption Uptake Measurements from a Calibrated Effusive Molecular Beam 255
23.2 Measurement of Absolute Sticking Coefficient at Desorption Temperature 257
References 259
24 Mass Spectrometry 260
24.1 Shielded Quadrupole Mass Spectrometers---Temperature-Programmed Desorption 260
24.2 Enhanced Signal-to-Noise in Quadrupole Mass Spectrometers 263
24.3 Elimination of Spurious Electron Emission from a Quadrupole Mass Spectrometer 266
24.4 Ta Mass Spectrometer Filament 266
24.5 Modulated QMS Ion Source for Enhanced Sensitivity 268
24.6 Line-of-Sight Mass Spectrometry for Thermal Desorption 270
24.7 Mass Spectrometer Calibration by Molecular Decomposition 271
References 273
25 Temperature-Programmed Desorption/Reaction 274
25.1 Thermal Desorption---Angular Resolved 274
25.2 Magic-Angle Thermal Desorption Mass Spectroscopy 276
25.3 High-Temperature Thermal Desorption Spectroscopy 278
25.4 Automated Temperature Programmed Desorption (TPD) Apparatus 279
25.5 Scanning Kinetic Spectroscopy---A Survey Method for Investigation of Surface Reaction Processes 281
25.6 Temperature-Programmed Reaction Spectroscopy (TPRS) 283
References 285
26 Gas Chromatography---Enhanced Sensitivity 287
26.1 Gas Chromatography---Sensitivity Enhancement 287
Reference 288
27 Work Function, Tunneling Spectroscopy and Ellipsometry 289
27.1 Work Function Changes Using Retarding Diode Method 289
27.2 Work Function Measurements Using an Electron Gun 291
27.3 Work Function and Electron Reflection Coefficient Measurements with the Shelton Diode 293
27.4 Improved Piezoelectric Drive Kelvin Probe 295
27.5 Improved Electromagnetic Drive Kelvin Probe 297
27.6 Kelvin Probe---High Temperature Flow Reactor 299
27.7 Scanning Tunneling Spectroscopy (STS)---Compensation for Density of States of the Tip 300
27.8 Ellipsometry as a Tool for Studying Adsorption 302
References 303
28 Radioactive Adsorbates 305
28.1 Radiotracer Techniques for Surface Studies 305
References 307
29 Thin Film Deposition 308
29.1 Thin Film Deposition to Absolute Surface Coverages 308
29.2 Gold Evaporation Source 311
29.3 Ionization Gauge Measurement of Film Evaporation Rate 313
29.4 Reusable Quartz Crystals for Film Thickness Measurement 313
29.5 Hybrid Thin Film Deposition Processes---Stable and Metastable Films 316
29.6 Sputter-Coating Inner Walls of Tubes 316
References 318
30 Infrared Spectroscopy 320
30.1 Infrared Reflection Absorption Spectrometer 320
30.2 IRAS Measurements at High Pressure 322
30.3 Internal Reflection IR Spectroscopy---Silicon 323
30.4 Internal Reflection IR Spectroscopy---Gallium Arsenide 326
30.5 Infrared Spectroscopy---Continuous Pumping of Detector Dewar 327
30.6 Rapid IR Spectrometer Purge After Cell Transfer---Using Rubber Sleeves 328
References 330
31 Calorimetric Heats of Adsorption---Single Crystals 332
31.1 Measurement of the Calorimetric Heat of Adsorption on Ultrathin Metal Single Crystals 332
31.2 Improved Adsorption Calorimeter for Single Crystals at 100--350 K 333
References 335
32 Surface Debye Temperature 336
32.1 Measuring the Surface Debye Temperature of a Single Crystal 336
References 338
33 Friction and Fracture 339
33.1 UHV Tribometer for Measuring the Coefficient of Friction 339
33.2 Pin-on-Disk Measurement---UHV 341
33.3 UHV Fracture Stage for Surface Analysis After Fracture 341
References 343
Part IVThermal Control 344
34 Heating Samples 345
34.1 Electronic Temperature Programmer---Metal Crystals 345
34.2 Temperature Programming of Metal and Semiconductor Crystals 347
34.3 Mounting Nonweldable Crystals for Resistive Heating and Cooling 350
34.4 Strain-Free Single Crystal Mounting Azimuthal Motion 351
34.5 Heating Silicon Crystals and Temperature Measurements 352
34.6 Avoiding Extraneous Electrical Effects Owing to Heating Crystals 355
34.7 Electron Bombardment Crystal Heating 357
34.8 Indirect Sample Heating 359
34.9 Indirect Heating of Compound Semiconductors 361
34.10 Heating Design---Insulator Crystals 362
34.11 Cement Mounting---Semiconductor Crystals 364
34.12 Low-Stress Mount for Fragile Semiconductor Crystals 365
34.13 Radiation Heating of Crystals Through Glass Windows 367
34.14 Pyrolytic Graphite Heating Element for UHV 368
34.15 Heater---Paint-on Type 370
34.16 Mounting High-Temperature Tungsten Filaments 371
34.17 Rotatable Single Crystal 371
34.18 Radiation-Heated Evaporator 374
References 374
35 Cooling Samples 377
35.1 6 K---Cryogenic Crystal Holder 377
35.2 Cooling Crystals by Contact with a Thermal Reservoir 379
35.3 Cooling Samples on Manipulators---Thermal Conductivity Issues 379
35.4 Vacuum-Jacketed Cryogenic Manipulator Rod 382
35.5 Manipulator Component with Cryogenic Azimuthal Rotation 384
35.6 Cooling Using Direct Contact 385
35.7 Cooling Reservoir---Horizontal Manipulator 386
35.8 Cryogenic Connections 388
35.9 Sample Cooling Using Thermal Braid 388
35.10 Flexible Cooling Reservoir 390
35.11 Enhanced Cooling Using Liquid Nitrogen 390
35.12 Level Alarm-Liquid Nitrogen 392
35.13 Liquid Nitrogen Reservoir---Non-leaking 394
35.14 Cryogenic Cooling to Below 4 K---Photon Stimulated Desorption of Adsorbed He 395
35.15 Static Temperature Control by Mixing Gas Streams 397
35.16 Gas Thermal Switch 397
References 400
36 Temperature Measurements 401
36.1 Tungsten-Rhenium Thermocouples---Calibration Over a Wide Temperature Range 401
36.2 Measuring Temperatures of Hot Filaments 403
36.3 Pyrometric Measurement of Temperatures 405
36.4 Pyrometer Measurements Through Windows Coated Inadvertently with Variable-Thickness Thin Films 407
36.5 Calibration Point for Optical Pyrometer Used for Silicon 409
36.6 Control of Silicon Temperature Using Resistivity 411
References 413
Part VDelivery of Adsorbates to Surfaces 414
37 Gases 415
37.1 Design and Performance of Microcapillary Array Beam Doser 415
37.2 Gas Handling System for Array Beam Doser 417
37.3 Calibration and Use of Array Beam Doser 419
37.4 Sticking Coefficient and Surface Reactivity 420
37.5 Beam Doser Shutoff---Condensable Gases 422
37.6 Neutral Beam Intensity Measurement Using a Stagnation Detector 423
37.7 Low Deadspace Aperture Valve for Repetitive Gas Dosing 424
37.8 Gas Flow Regulation---Squeeze Valve 427
37.9 Retractable Beam Doser with Convenient On-Off Control 428
References 429
38 Evaporation Sources 431
38.1 Degassing Evaporation Sources 431
38.2 Metal Evaporation Sources for Downward Evaporation 433
38.3 Ultralow Coverage Metal Evaporation 434
38.4 Congruent Evaporation of Multicomponent Materials 436
38.5 Evaporator for Eutectic-Forming Metals 438
38.6 Simple Lithium Metal Evaporation Source 438
38.7 Aluminum Evaporation Sources---Long Lived 440
38.8 Cr Evaporator Sources of Compact Design 442
38.9 Electron Beam Evaporator for Refractory Materials 443
38.10 Small Electron Beam Evaporator for Refractory Metals 445
38.11 Electron Beam Evaporator 447
38.12 Break-Seal Ampoule Doser 449
38.13 Cadmium Sulfide Evaporation Source 450
38.14 Arsenic Atom Source 450
38.15 Portable Microevaporator for Depositing Low Coverages of Single Atoms 453
38.16 Nanoscale Templating of Close-Packed C60 Nanostructures 454
38.17 Quantitative Molecular Beam Dosing of Slightly Volatile Organics 454
38.18 Organic Doser 458
38.19 Vapor Deposition of Organic Thin Films 458
38.20 Evaporator for Organic Film Deposition 459
References 462
39 Ions 464
39.1 Solid State Cesium Ion Gun Source 464
39.2 Alkaline Earth Metal Ion Sources 466
References 468
40 Active Gases and Species 469
40.1 High Flux Atomic Hydrogen Sources---Thermal 469
40.2 Atomic Hydrogen Beam Source---Radio Frequency Driven 472
40.3 Atomic Fluorine Source 473
40.4 Alkali Metal Sources 475
40.5 Thermal Source of Methyl Free Radicals 477
40.6 Production, Storage, and Use of Ozone 478
40.7 Ozone Generator and Molecular Beam Doser Source 480
40.8 Detection of Ozone or Atomic Oxygen by Oxidation of Silver Films 482
40.9 Purity of Ir and Pt Hot Filament Sources for Atomic Oxygen Production 483
40.10 Pure Hydrogen Peroxide Doser for Ultrahigh Vacuum 485
References 486
41 Electrochemical Sources and Devices 489
41.1 Electrochemical Sulfur Source 489
41.2 Electrochemical Halogen Sources 490
41.3 Electrochemical I2 Doser 493
41.4 Electrochemical Device Working in UHV 494
References 496
42 Gas Purification 497
42.1 Gas Purification for Experiments at High Pressures 497
42.2 Production and Purity Measurement for Extremely Pure He 499
42.3 Purification of Gases by Cryogenic or Gettering Methods 501
42.4 Gas Purification by Permeation Through Metals 503
42.5 O2 Source---Solid State 505
42.6 Reusable Sample Holder for Hydrogen Permeation Studies 505
References 506
43 Liquid Handling in UHV 508
43.1 Adding Liquid to Atomically Clean Surfaces 508
Reference 509
Part VIUHV Windows 510
44 Spectroscopic Windows 511
44.1 Mounting Infrared Windows on UHV Systems 511
44.2 Windows for Vacuum UV Transmission into Ultrahigh Vacuum Systems 514
44.3 Construction of Be Windows for Ultrahigh Vacuum Use 516
44.4 Bakeable Aluminum Ultrahigh Vacuum Window 518
44.5 Metal Thin Foil Windows---Welding 519
44.6 Preparation of Large-Area Si Single Crystal Windows 519
44.7 Strain-Free Optical Window Mounting 522
References 523
45 Observation Windows 525
45.1 Shielded Observation Window 525
45.2 Heated Internal Window for Prevention of Film Deposition 526
45.3 UHV Glass Window Seal---Low Optical Distortion 527
45.4 Zero-Length Window Assembly 529
References 530
Part VIISurface Preparation Methods 531
46 Cleaning Metal and Semiconductor Crystals---Examples 532
46.1 Surface Segregation and the Cleaning of Metal Single Crystals 532
46.2 Chemical Method to Measure and Remove Carbon from Pd 535
46.3 Surface Cleaning Procedures---Silicon 537
46.4 Preparation of Atomically Clean Tungsten Single Crystals 540
References 540
Part VIIIHigh-Area Solids 541
47 Infrared Cells 542
47.1 Infrared Cell for Adsorption Studies on Supported Catalysts 542
47.2 Wide-Temperature-Range IR Cell for High-Area Solids 544
47.3 Measurements of Diffusion Through Powders Using Transmission Infrared Spectroscopy 547
47.4 Using Transmission Infrared Spectroscopy to Witness Diffusion into Core-Shell Structures 549
47.5 Diffusion in Powders as Measured by Transmission IR Spectroscopy 549
47.6 Transmission IR Spectroscopy Through Opaque Materials 551
References 554
48 Adsorption/Desorption---Thermal 555
48.1 Adsorption and Desorption from High-Area Solids 555
48.2 Thermal Desorption from High Area Materials 557
48.3 Microcalorimetric Studies of Adsorption Heat on Powders 560
48.4 Chemical Vapor Synthesis of Oxide Nanoparticles 562
References 563
Part IXSafety 564
49 Protecting the Vacuum System 565
49.1 Delay Circuit for Turbopumping Protection Against Vacuum Loss from Power Interruptions 565
49.2 Fast-Closing Beam Valve for UHV Chamber Protection 567
49.3 Safety System for Oil Diffusion-Pumped UHV Systems 568
49.4 Folding Linear Magnetic Translator 570
References 571
50 Protecting Personnel 573
50.1 Electrical Shocks in the Laboratory 573
50.2 Accidental Electrical Charging from Ionization Gauge 574
Reference 576
Appendix A 577
Appendix B 580
Index 625