185:
244:
33:
377:(SKP), which uses a wire probe of tens to hundreds of microns in size, can be used. In either case the capacitance change is not known—instead, a compensating DC voltage is added to cancel the Volta potential so that no current is induced by the change in capacitance. This compensating voltage is the negative of the Volta potential.
207:
When two metals are electrically isolated from each other, an arbitrary potential difference may exist between them. However, when two different neutral metal surfaces are brought into electrical contact (even indirectly, say, through a long electro-conductive wire), electrons will flow from the
361:
is the Volta potential. It follows therefore that the value of the potential can be measured by varying the capacitance between the materials by a known amount (e.g., by moving the objects further from each other) and measuring the displaced charge that flows through the wire that connects them.
212:
to the metal with the lower Fermi level until the Fermi levels in the two phases are equal. Once this has occurred, the metals are in thermodynamic equilibrium with each other (the actual number of electrons that passes between the two phases is usually small). Just because the Fermi levels are
262:
The Volta potential, however, corresponds to a real electric field in the spaces between and around the two metal objects, a field generated by the accumulation of charges at their surfaces. The total charge
365:
The Volta potential difference between a metal and an electrolyte can be measured in a similar fashion. The Volta potential of a metal surface can be mapped on very small scales by use of a
336:
359:
304:
281:
165:. Specifically, it is the potential difference between a point close to the surface of the first metal and a point close to the surface of the second metal (or
228:
differences between the metals' surfaces. Just like the work function, the Volta potential depends sensitively on surface state, contamination, and so on.
473:
213:
equal, however, does not mean that the electric potentials are equal. The electric potential outside each material is controlled by its
468:
116:
50:
97:
54:
69:
366:
391:
76:
247:
Kelvin probe energy diagram at flat vacuum configuration, used for measuring Volta potential between sample and probe.
43:
478:
162:
83:
370:
193:
150:
65:
251:
The Volta potential can be significant (of order 1 volt) but it cannot be measured directly by an ordinary
184:
374:
243:
406:
309:
386:
188:
When the two metals depicted here are in thermodynamic equilibrium with each other as shown (equal
341:
396:
401:
255:. A voltmeter does not measure vacuum electrostatic potentials, but instead the difference in
224:
an intrinsic property of the two bulk metals under consideration, but rather is determined by
90:
173:
146:
217:, and so dissimilar metals can show an electric potential difference even at equilibrium.
289:
266:
462:
225:
214:
200:
422:
412:
284:
256:
237:
209:
189:
166:
158:
32:
452:
259:
between the two materials, a difference that is exactly zero at equilibrium.
252:
17:
441:
154:
442:
IUPAC Gold Book, definition of contact (Volta) potential difference.
373:. Over larger areas on the order of millimeters to centimeters, a
417:
26:
344:
312:
292:
269:
57:. Unsourced material may be challenged and removed.
353:
330:
298:
275:
232:Measurement of Volta potential (Kelvin probe)
8:
283:over each object's surface depends on the
343:
311:
306:between the two objects, by the relation
291:
268:
117:Learn how and when to remove this message
242:
183:
434:
7:
55:adding citations to reliable sources
199:is not flat due to a difference in
172:The Volta potential is named after
345:
322:
180:Volta potential between two metals
25:
161:) that are in contact and are in
31:
331:{\displaystyle Q=C\Delta \psi }
42:needs additional citations for
1:
367:Kelvin probe force microscope
392:Absolute electrode potential
354:{\displaystyle \Delta \psi }
139:contact potential difference
495:
474:Electrochemical potentials
235:
143:outer potential difference
135:Volta potential difference
163:thermodynamic equilibrium
145:, Δψ, or "delta psi") in
469:Electrochemical concepts
236:Not to be confused with
371:atomic force microscopy
220:The Volta potential is
194:electrostatic potential
153:difference between two
151:electrostatic potential
355:
332:
300:
277:
248:
208:metal with the higher
204:
157:(or one metal and one
375:scanning Kelvin probe
356:
333:
301:
278:
246:
187:
407:Potential difference
342:
310:
290:
267:
51:improve this article
387:Electrode potential
397:Electric potential
351:
328:
296:
273:
249:
205:
402:Galvani potential
299:{\displaystyle C}
276:{\displaystyle Q}
127:
126:
119:
101:
66:"Volta potential"
16:(Redirected from
486:
479:Alessandro Volta
453:
450:
444:
439:
360:
358:
357:
352:
337:
335:
334:
329:
305:
303:
302:
297:
282:
280:
279:
274:
174:Alessandro Volta
147:electrochemistry
122:
115:
111:
108:
102:
100:
59:
35:
27:
21:
494:
493:
489:
488:
487:
485:
484:
483:
459:
458:
457:
456:
451:
447:
440:
436:
431:
383:
340:
339:
308:
307:
288:
287:
265:
264:
241:
234:
182:
131:Volta potential
123:
112:
106:
103:
60:
58:
48:
36:
23:
22:
15:
12:
11:
5:
492:
490:
482:
481:
476:
471:
461:
460:
455:
454:
445:
433:
432:
430:
427:
426:
425:
420:
415:
410:
404:
399:
394:
389:
382:
379:
350:
347:
327:
324:
321:
318:
315:
295:
272:
233:
230:
192:), the vacuum
181:
178:
125:
124:
39:
37:
30:
24:
14:
13:
10:
9:
6:
4:
3:
2:
491:
480:
477:
475:
472:
470:
467:
466:
464:
449:
446:
443:
438:
435:
428:
424:
421:
419:
416:
414:
411:
408:
405:
403:
400:
398:
395:
393:
390:
388:
385:
384:
380:
378:
376:
372:
368:
363:
348:
325:
319:
316:
313:
293:
286:
270:
260:
258:
254:
245:
239:
231:
229:
227:
226:work function
223:
218:
216:
215:work function
211:
202:
201:work function
198:
195:
191:
186:
179:
177:
175:
170:
168:
164:
160:
156:
152:
148:
144:
140:
136:
133:(also called
132:
121:
118:
110:
107:December 2019
99:
96:
92:
89:
85:
82:
78:
75:
71:
68: –
67:
63:
62:Find sources:
56:
52:
46:
45:
40:This article
38:
34:
29:
28:
19:
448:
437:
423:Volta effect
413:Band bending
364:
261:
250:
221:
219:
206:
196:
190:Fermi levels
171:
142:
138:
134:
130:
128:
113:
104:
94:
87:
80:
73:
61:
49:Please help
44:verification
41:
18:Kelvin probe
369:, based on
285:capacitance
257:Fermi level
238:Kelvin clip
210:Fermi level
167:electrolyte
159:electrolyte
463:Categories
429:References
77:newspapers
409:(voltage)
349:ψ
346:Δ
326:ψ
323:Δ
253:voltmeter
149:, is the
381:See also
338:, where
91:scholar
155:metals
93:
86:
79:
72:
64:
98:JSTOR
84:books
418:Volt
129:The
70:news
222:not
169:).
53:by
465::
176:.
141:,
137:,
320:C
317:=
314:Q
294:C
271:Q
240:.
203:.
197:ϕ
120:)
114:(
109:)
105:(
95:·
88:·
81:·
74:·
47:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.