X-ray Photoemission spectroscopy 4.1.4



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4.1.4 X-ray Photoemission spectroscopy

Interaction of a photon of energy hν with an electron in an atomic energy level of binding energy E_B occurs by transfer of all the photon energy to the electron. If hv is greater than E_B, a photoelectron is ejected from the atom with a kinetic energy given by

E_Kin = hv − E_B

(1)

When the atom forms part of a solid, there is a work function term to be subtracted from the right-hand side of (1), but it is comparatively small and nearly constant. Measured E_Kin values thus reflect the E_B values directly, so that measurement of E_Kin provides elemental analysis.

In X-ray photoemission spectroscopy the two sources in most common use are magnesium and aluminium, the principal line energies used being the Kα_{1, 2}, 1253.6 eV for magnesium and 1486.6 eV for aluminium. Since the kinetic energies of the photoelectrons will therefore be in the range 0–1500 eV, the paths of the electrons (see section 4.5.2) will be very short, and the photoelectrons must originate at, or very close to, the true surface if they are to escape and be measured. Like Auger spectroscopy, X-ray photoelectron spectroscopy is thus a surface-specific technique.

The tables list the photoelectron kinetic energies expected for all elements from H to U, for Mg Kα, and for Al Kα, excitation, respectively, to the nearest electron-volt. Where the element exists as a pure elemental non-volatile solid, the values will correspond to that state with reasonable accuracy, but for other elements, particularly the non-metallic ones, the values must be regarded as approximate since shifts of several eV can occur between different states of chemical combination of an element. The reference point for all the values is a binding energy for the Au 4f_7/2 level assumed to be 84.0 eV.

For further reading the reader is referred to the books by Briggs and Seah (1990) and Rivière (1990). The former gives details of high accuracy calibration values and the positions for different chemical states.

References

D. Briggs and M. P. Seah (1990) Practical Surface Analysis Vol 1: Auger and X-ray Photoelectron Spectroscopy, Wiley, Chichester.
J. C. Rivière (1990) Surface Analytical Techniques, University Press, Oxford.

Table 1

Photoelectron kinetic energies, to nearest electron-volt and referred to the binding energy Au 4f_7/2 =84.0 eV, using Mg K_α excitation. The energy of the most intense photoelectron peak for each element is underlined.

		1s	2s	2p_1/2	2p_3/2	3s	3p_1/2	3p_3/2	3d_3/2	3d_5/2	4s	4p_1/2	4p_3/2	4d_3/2	4d_5/2	4f_5/2	4f_7/2	5s	5p_1/2	5p_3/2	5d_3/2	5d_5/2	5f_5/2	5f_7/2	6s	6p_1/2	6p_3/2	6d_3/2	6d_5/2
1	H .	1239
2	He .	1228
3	Li .	1198
4	Be .	1141
5	B .	1064		1248
6	C .	969		1246
7	N .	854		1243
8	O .	720	1229	1245
9	F .	567	1221	1244
10	Ne .	386	1207	1234
11	Na .	180	1189	1221		1251
12	Mg .		1163	1201		1250
13	Al .		1135	1179	1180	1251	1250
14	Si .		1104	1152	1153	1244	1249
15	P .		1063	1116	1117	1236	1242
16	S .		1023	1087	1088	1236	1244
17	Cl		982	1051	1052	1235	1246
18	Ar .		932	1005	1007	1227	1240
19	K .		875	956	959	1219	1235				1250
20	Ca		815	902	906	1209	1227				1247
21	Sc .		752	846	850	1199	1220		1245		1250
22	Ti .		689	791	797	1192	1218		1249		1249
23	V .		624	732	740	1186	1215		1250		1249
24	Cr .		558	669	678	1178	1210		1250		1249
25	Mn .		483	600	612	1169	1204		1249		1249
26	Fe .		406	531	544	1160	1198		1249		1249
27	Co .		327	459	474	1152	1193		1250		1248
28	Ni .		244	381	398	1141	1184		1249		1248
29	Cu .		156	301	321	1133	1179		1251		1250
30	Zn .		59	210	233	1117	1166		1244		1248
31	Ga .			110	137	1094	1146	1150	1235			1251
32	Ge .			5	36	1072	1125	1132	1224			1249
33	As .					1049	1106	1112	1211			1250
34	Se .					1021	1084	1091	1196			1247
35	Br .					996	1063	1071	1182	1183	1225	1247	1248
36	Kr .					963	1030	1039	1164		1228	1242
37	Rb .					930	1005	1014	1141	1142	1223	1238	1239
38	Sr .					895	973	983	1117	1119	1215	1233
39	Y .					859	940	952	1093	1095	1207	1227		1249
40	Zr .					822	908	922	1070	1072	1201	1224		1249
41	Nb .					784	874	889	1045	1048	1194	1219		1249
42	Mo .					748	843	860	1022	1025	1191	1218		1251
43	Tc .					708	808	827	996	1000	1184	1214		1250
44	Ru .					667	770	792	969	973	1178	1209		1250
45	Rh .					625	731	756	941	945	1171	1205		1250
46	Pd .					583	693	721	912	918	1166	1201		1251
47	Ag . .					535	650	681	880	886	1157	1190	1197	1249
48	Cd . .					482	602	636	842	849	1145	1186		1243
49	In . .					427	550	588	802	809	1131	1175		1236					1252
50	Sn .					369	496	538	759	768	1116	1164		1229				1252	1251
51	Sb .					309	441	487	716	725	1100	1154		1221				1246	1250
52	Te . .					246	383	434	670	680	1084	1142		1213				1241	1250
53	I . .					180	322	378	621	633	1066	1130		1203				1239	1249
54	Xe .					107	253	315	567	580	1044	1106		1189				1234	1245
55	Cs .					35	187	255	513	527	1022	1080	1091	1174	1176			1230	1239	1241
56	Ba . .						116	190	456	472	999	1061	1073	1160	1163			1213	1236	1238
57	La . .						48	129	404	421	982	1047	1061	1154				1220	1238
58	Ce . .							67	351	369	963	1029	1045	1142		1252		1215	1233
59	Pr . .							10	301	321	948	1016	1035	1139		1250		1215	1230
60	Nd . .								253	275	937	1009	1028	1135		1251		1215	1231
61	Pm . .								201	226	921	997	1015	1132		1248		1214	1230
62	Sm . .								146	172	907	987	1005	1123		1247		1215	1231
63	Eu . .								92	122	892	969	996	1119		1252		1221	1230
64	Gd . .								35	67	877	964	982	1112		1252		1216	1232
65	Tb . .									11	855	942	967	1105		1250		1213	1227
66	Dy . .										836	921	960	1098		1248		1190	1226
67	Ho . .										817	909	946	1091		1249		1201	1232
68	Er . .										803	886	932	1076	1085	1248		1193	1223
69	Tm . .										781	867	916	1073		1247		1199	1229
70	Yb . .										765	856	909	1054	1068	1246		1198	1229
71	Lu . .										746	842	893	1048	1057	1246		1196	1224		1247
72	Hf . .										714	815	872	1029	1039	1234	1235	1188	1214	1222	1245
73	Ta . .										687	788	848	1011	1023	1226	1227	1181	1208	1216	1247
74	W . .										657	761	827	994	1007	1216	1219	1175	1206	1217	1246
75	Re . .										627	735	808	979	992	1210	1212	1170	1207	1218	1248
76	Os . .										598	706	784	963	980	1200	1202	1169	1194	1207	1252
77	Ir . .										562	675	758	941	958	1189	1192	1157	1189	1202	1249
78	Pt . .										530	643	733	922	939	1178	1181	1151	1187	1201	1250
79	Au . .										494	609	707	900	919	1166	1170	1145	1181	1199	1250
80	Hg . .										452	576	681	874	893	1150	1154	1132	1172	1195	1246
81	Tl . .										407	531	643	846	866	1130	1134	1116	1153	1177	1237	1239			1249
82	Pb . .										359	489	608	817	840	1110	1114	1105	1148	1166	1231	1233			1249	1252
83	Bi . .										314	447	574	789	812	1091	1095	1093	1136	1160	1226	1228			1244	1250
84	Po . .										257	401	547	752	779	1066	1071	1075	1120	1148	1221				1240	1247
85	At . .										210	366	512	719	745	1042		1057	1104	1137	1212				1234	1244
86	Rn . .										155	323	484	686	711	1014		1038	1088	1125	1204				1226	1241
87	Fr . .										99	272	442	649	675	984		1018	1070	1112	1194				1218	1237
88	Ra . .										44	195	373	617	650	954		998	1052	1100	1185				1209	1234
89	Ac . .											172	362	578	613	933		980	1037	1085	1172				1200	1220		1250
90	Th . .											84	285	538	576	908	917	962	1023	1071	1158	1165			1193	1203	1209	1250
91	Pa . .											28	246	509	544	881	893	943	1029		1158		1219		1187	1210		1249
92	U . .												208	472	515	861	872	929	993	1057	1147	1156	1215		1182	1210	1220	1248

Table 2

Photoelectron kinetic energies, to nearest electron-volt and referred to the binding energy Au 4f_7/2 84.0 eV, using Al K_α excitation. The energy of the most intense photoelectron peak for each element is underlined.

		1s	2s	2p_1/2	2p_3/2	3s	3p_1/2	3p_3/2	3d_3/2	3d_5/2	4s	4p_1/2	4p_3/2	4d_3/2	4d_5/2	4f_5/2	4f_7/2	5s	5p_1/2	5p_3/2	5d_3/2	5d_5/2	5f_5/2	5f_7/2	6s	6p_1/2	6p_3/2	6d_3/2	6d_5/2
1	H . . .	1472
2	He . . .	1461
3	Li . . .	1431
4	Be . . .	1374
5	B . . .	1297		1481
6	C . . .	1202		1479
7	N . . .	1087		1476
8	O . . .	953	1462	1478
9	F . . .	800	1454	1477
10	Ne . . .	619	1440	1467
11	Na . . .	413	1422	1454		1484
12	Mg . . .	180	1396	1434		1483
13	Al . . .		1368	1412	1413	1484	1483
14	Si . . .		1337	1385	1386	1477	1482
15	P . . .		1296	1349	1350	1469	1475
16	S . . .		1256	1320	1321	1469	1477
17	Cl . . .		1215	1284	1285	1468	1479
18	Ar . . .		1165	1238	1240	1460	1473
19	K . . .		1108	1189	1192	1452	1468				1483
20	Ca . . .		1048	1135	1139	1442	1460				1480
21	Sc . . .		985	1079	1083	1432	1453		1478		1483
22	Ti . . .		922	1024	1030	1425	1451		1482		1482
23	V . . .		857	965	973	1419	1448		1483		1482
24	Cr . . .		791	902	911	1411	1443		1483		1482
25	Mn . . .		716	833	845	1402	1437		1482		1482
26	Fe . . .		639	764	777	1393	1431		1482		1482
27	Co . . .		560	692	707	1385	1426		1483		1481
28	Ni . . .		477	614	631	1374	1417		1482		1481
29	Cu . . .		389	534	554	1366	1412		1484		1483
30	Zn . . .		292	443	466	1350	1399		1477		1481
31	Ga . . .		189	343	370	1327	1379	1383	1468			1484
32	Ge . . .		71	238	269	1305	1358	1365	1457			1482
33	As . . .			127	162	1282	1339	1345	1444			1483
34	Se . . .			9	50	1254	1317	1324	1429			1480
35	Br . . .					1229	1296	1304	1415	1416	1458	1480	1481
36	Kr . . .					1196	1263	1272	1397		1461	1475
37	Rb . . .					1163	1238	1247	1374	1375	1456	1471	1472
38	Sr . . .					1128	1206	1216	1350	1352	1448	1466
39	Y . . .					1092	1173	1185	1326	1328	1440	1460		1482
40	Zr . . .					1055	1141	1155	1303	1305	1434	1457		1482
41	Nb . . .					1017	1107	1122	1278	1281	1427	1452		1482
42	Mo . . .					981	1076	1093	1255	1258	1424	1451		1484
43	Tc . . .					941	1041	1060	1229	1233	1417	1447		1483
44	Ru . . .					900	1003	1025	1202	1206	1411	1442		1483
45	Rh . . .					858	964	989	1174	1178	1404	1438		1483
46	Pd . . .					816	926	954	1145	1151	1399	1434		1484
47	Ag . . .					768	883	914	1113	1119	1390	1423	1430	1482
48	Cd . . .					715	835	869	1075	1082	1378	1419		1476
49	In . . .					660	783	821	1035	1042	1364	1408		1469					1485
50	Sn . . .					602	729	771	992	1001	1349	1397		1462				1485	1484
51	Sb . . .					542	674	720	949	958	1333	1387		1454				1479	1483
52	Te . . .					479	616	667	903	913	1317	1375		1446				1474	1483
53	I . . .					413	555	611	854	866	1299	1363		1436				1472	1482
54	Xe . . .					340	486	548	800	813	1277	1339		1422				1467	1478
55	Cs . . .					268	420	488	746	760	1255	1313	1324	1407	1409			1463	1472	1474
56	Ba . . .					193	349	423	689	705	1232	1294	1306	1393	1396			1446	1469	1471
57	La . . .					124	281	362	637	654	1215	1280	1294	1387				1453	1471
58	Ce . . .					51	213	300	584	602	1196	1262	1278	1375		1485		1448	1466
59	Pr . . .						148	243	534	554	1181	1249	1268	1372		1483		1448	1463
60	Nd . . .						83	188	486	508	1170	1242	1261	1368		1484		1448	1464
61	Pm . . .						14	129	434	459	1154	1230	1248	1365		1481		1447	1463
62	Sm . . .							66	379	405	1140	1220	1238	1356		1480		1448	1464
63	Eu . . .							5	325	355	1125	1202	1229	1352		1485		1454	1463
64	Gd . . .								268	300	1110	1197	1215	1345		1485		1449	1465
65	Tb . . .								210	244	1088	1175	1200	1338		1