1133:
techniques. The field cycling involves three steps: preparation, evolution and detection. In the preparation stage, a field is applied in order to magnetize the nuclear spins. Then the field is suddenly switched to zero to initiate the evolution interval and the magnetization evolves under the zero-field
Hamiltonian. After a time period, the field is again switched on and the signal is detected inductively at high field. In a single field cycle, the magnetization observed corresponds only to a single value of the zero-field evolution time. The time-varying magnetization can be detected by repeating the field cycle with incremented lengths of the zero-field interval, and hence the evolution and decay of the magnetization is measured point by point. The Fourier transform of this magnetization will result to the zero-field absorption spectrum.
73:. In ZULF experiments the sample is moved through a low field magnet into the "zero field" region where the dominant interactions are nuclear spin-spin couplings, and the coupling between spins and the external magnetic field is a perturbation to this. There are a number of advantages to operating in this regime: magnetic-susceptibility-induced line broadening is attenuated which reduces inhomogeneous broadening of the spectral lines for samples in heterogeneous environments. Another advantage is that the low frequency signals readily pass through conductive materials such as metals due to the increased skin depth; this is not the case for high-field NMR for which the sample containers are usually made of glass, quartz or ceramic. High-field NMR employs
114:
1124:
spins to zero field in order to convert the Zeeman populations into zero-field eigenstates adiabatically and subsequently in applying a constant magnetic field pulse to induce a coherence between the zero-field eigenstates. In the simple case of a heteronuclear pair of J-coupled spins, both these excitation schemes induce a transition between the singlet and triplet-0 states, which generates a detectable oscillatory magnetic field. More sophisticated pulse sequences have been reported including selective pulses, two-dimensional experiments and decoupling schemes.
1148:. SQUIDs have high sensitivity, but require cryogenic conditions to operate, which makes them practically somewhat difficult to employ for the detection of chemical or biological samples. Magnetoresistive sensors are less sensitive, but are much easier to handle and to bring close to the NMR sample which is advantageous since proximity improves sensitivity. The most common sensors employed in ZULF NMR experiments are optically-pumped magnetometers, which have high sensitivity and can be placed in close proximity to an NMR sample.
1174:
i.e., at ultralow field spin-spin couplings dominate and the Zeeman interaction is a perturbation. The boundary between low and high field is more ambiguous and these terms are used differently depending on the application or research topic. In the context of ZULF NMR, the boundary is defined as the field at which chemical shift differences between nuclei of the same isotopic species in a sample match the spin-spin couplings.
1111:
1157:
31:
1102:
NMR experiments require creating a transient non-stationary state of the spin system. In conventional high-field experiments, radio frequency pulses tilt the magnetization from along the main magnetic field direction to the transverse plan. Once in the transverse plan, the magnetization is no longer
1173:
rate, i.e., at zero field the nuclear spins relax faster than they precess about the external field. The boundary between ultralow and low field is usually defined as the field at which Larmor frequency differences between different nuclear spin species match the spin-spin (J or dipolar) couplings,
1164:
The boundaries between zero-, ultralow-, low- and high-field NMR are not rigorously defined, although approximate working definitions are in routine use for experiments involving small molecules in solution. The boundary between zero and ultralow field is usually defined as the field at which the
1123:
In ZULF experiments, constant magnetic field pulses are used to induce non-stationary states of the spin system. The two main strategies consist of (1) switching of the magnetic field from pseudo-high field to zero (or ultra-low) field, or (2) of ramping down the magnetic field experienced by the
117:
A comparison between high-field and zero-field NMR spectra of a sample containing a mixture of -acetic acid and -bromoacetic acid. In the high field, the H and C nuclear spin species precess at different frequencies, yielding distinct H and C spectra with the J-coupling perturbation splitting the
90:
made it possible to detect NMR signals directly in the ZULF regime. Previous ZULF NMR experiments relied on indirect detection where the sample had to be shuttled from the shielded ZULF environment into a high magnetic field for detection with a conventional inductive pick-up coil. One successful
1118:
field, with H polarization about 4 times higher than that of C spins. This is a stationary state at high field. If the field is non-adiabatically (rapidly) switched off, the state starts to evolve. The polarization oscillates between the H and C spins at the J-coupling frequency (210 Hz in this
1074:
Before signals can be detected in a ZULF NMR experiment, it is first necessary to polarize the nuclear spin ensemble, since the signal is proportional to the nuclear spin magnetization. There are a number of methods to generate nuclear spin polarization. The most common is to allow the spins to
1132:
NMR signals are usually detected inductively, but the low frequencies of the electromagnetic radiation emitted by samples in a ZULF experiment makes inductive detection impractical at low fields. Hence, the earliest approach for measuring zero-field NMR in solid samples was via field-cycling
118:
resonance into doublet, triplet or quartet multiplet patterns. At zero field, there is no Larmor precession and the resonance frequencies are determined principally by the J-couplings. A notable feature is the narrow line width at zero field, owing to a lack of inhomogeneous broadening.
77:
to pick up the radiofrequency signals, but this would be inefficient in ZULF NMR experiments since the signal frequencies are typically much lower (on the order of hertz to kilohertz). The development of highly sensitive magnetic sensors in the early 2000s including
1177:
Note that these definitions strongly depend on the sample being studied, and the field regime boundaries can vary by orders of magnitude depending on sample parameters such as the nuclear spin species, spin-spin coupling strengths, and spin relaxation times.
1075:
thermally equilibrate in a magnetic field, and the nuclear spin alignment with the magnetic field due to the Zeeman interaction leads to weak spin polarization. The polarization generated in this way is on the order of 10 for tesla field-strengths.
463:
586:
102:
techniques. This can be as simple as polarizing the spins in a magnetic field followed by shuttling to the ZULF region for signal acquisition, and alternative chemistry-based hyperpolarization techniques can also be used.
342:
916:
1136:
The emergence of highly sensitive magnetometry techniques has allowed for the detection of zero-field NMR signals in situ. Examples include superconducting quantum interference devices (
1064:
1008:
972:
822:
786:
263:
199:
663:
636:
163:
349:
470:
859:
227:
747:
609:
717:
690:
1078:
An alternative approach is to use hyperpolarization techniques, which are chemical and physical methods to generate nuclear spin polarization. Examples include
1028:
936:
1532:
69:
to attenuate Earth’s magnetic field. This is in contrast to the majority of NMR experiments which are performed in high magnetic fields provided by
1390:
Sjolander, T.F.; Tayler, M.C.D.; King, J.P.; Budker, D.; Pines, A. (2017). "Transition-Selective Pulses in Zero-Field
Nuclear Magnetic Resonance".
1427:
Sjolander, T.F.; et al. (2017). "13C-decoupled J-coupling spectroscopy using two-dimensional nuclear magnetic resonance at zero-field".
1550:
1565:
113:
1214:"Chemical Reaction Monitoring using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers"
1079:
1357:
1262:
Put, Piotr; Pustelny, Szymon; Budker, Dmitry; Druga, Emanuel; Sjolander, Tobias F.; Pines, Alexander; Barskiy, Danila A. (2021).
1212:
Burueva, D.; Eills, J.; Blanchard, J.W.; Garcon, A.; Picazo Frutos, R.; Kovtunov, K.V.; Koptyug, I.; Budker, D. (June 8, 2020).
133:
1114:
The thermal equilibrium state of a H-C pair in high-field corresponds to a state in which both spins are polarized along the B
274:
1293:
Sheng, D.; Li, S.; Dural, N.; Romalis, M. (18 April 2013). "Subfemtotesla Scalar Atomic
Magnetometry Using Multipass Cells".
824:(and therefore the spin dynamics behavior of such a system) depends on the magnetic field. For example, in conventional NMR,
98:
Without a large magnetic field to induce nuclear spin polarization, the nuclear spins must be polarized externally using
1087:
107:
1083:
99:
165:), which in the case of liquid-state nuclear magnetic resonance may be split into two major terms. The first term (
50:
864:
62:
1107:) and so it begins to precess about the main magnetic field creating a detectable oscillating magnetic field.
1295:
70:
1218:
1551:
https://pines.berkeley.edu/publications/chemical-analysis-using-j-coupling-multiplets-zero-field-nmr-0
1545:
1480:
1429:
1314:
1187:
1531:
T. Theis, P. Ganssle, G. Kervern, S. Knappe, J. Kitching, M. P. Ledbetter, D. Budker and A. Pines; “
1160:
NMR resonances of a H-C spin pair with a 100 Hz J-coupling under different external magnetic fields.
1033:
977:
941:
791:
755:
232:
168:
458:{\displaystyle {\hat {H}}_{z}=-\hbar \sum _{a}\gamma _{a}(1-\sigma _{a}){\hat {I}}_{a}\cdot B_{0}}
1338:
1304:
641:
614:
581:{\displaystyle {\hat {H}}_{J}=-\hbar 2\pi \sum _{a>b}J_{ab}{\hat {I}}_{a}\cdot {\hat {I}}_{b}}
66:
139:
1445:
1409:
1330:
1244:
1166:
1141:
83:
827:
212:
1488:
1472:
1464:
1437:
1401:
1392:
1322:
1275:
1234:
1226:
1170:
722:
594:
74:
695:
668:
58:
1484:
1318:
1263:
1239:
1213:
1013:
921:
206:
1524:
M. P. Ledbetter, C. Crawford, A. Pines, D. Wemmer, S. Knappe, J. Kitching, D. Budker "
1559:
1362:
1192:
202:
1342:
1326:
1525:
91:
implementation was using atomic magnetometers at zero magnetic field working with
1279:
1492:
1441:
1010:. In contrast, at nanotesla fields, Larmor frequencies can be much smaller than
1377:
1104:
266:
17:
1405:
34:
A sample being investigated using NMR spectroscopy in a zero-field NMR setup.
1463:
Weitekamp, D.P.; Bielecki, A.; Zax, D.; Zilm, K.; Pines, A. (May 30, 1983).
1156:
1110:
30:
1449:
1413:
1334:
1248:
1230:
938:-coupling values which are typically Hz to hundreds of Hz. In this limit,
205:
interaction between spins and the external magnetic field, which includes
719:
is the external magnetic field experienced by all considered spins, and;
92:
54:
65:). ZULF NMR experiments typically involve the use of passive or active
665:
denotes the isotropic part of the chemical shift for the a-th spin;
591:
Here the summation is taken over the whole system of coupled spins;
1546:
https://pines.berkeley.edu/research/ultra-low-field-zero-field-nmr
1309:
1155:
1137:
1109:
1091:
112:
79:
29:
1264:"Zero- to Ultralow-Field NMR Spectroscopy of Small Biomolecules"
1145:
87:
1507:
53:(NMR) spectra of chemicals with magnetically active nuclei (
1533:
Parahydrogen-enhanced zero-field nuclear magnetic resonance
1526:
Optical detection of NMR J-spectra at zero magnetic field
337:{\displaystyle {\hat {H}}={\hat {H}}_{z}+{\hat {H}}_{J}}
1119:
example), and this gives rise to J-spectra in ZULF NMR.
57:
and greater) in an environment carefully screened from
861:
is typically larger than 1 T, so the Larmor frequency
1036:
1016:
980:
944:
924:
867:
830:
794:
758:
725:
698:
671:
644:
617:
597:
473:
352:
277:
235:
215:
171:
142:
918:of H exceeds tens of MHz. This is much larger than
1058:
1022:
1002:
966:
930:
910:
853:
816:
780:
749:is the J-coupling constant between spins a and b.
741:
711:
684:
657:
630:
603:
580:
457:
336:
257:
221:
193:
157:
132:Free evolution of nuclear spins is governed by a
1084:spin-exchange optical pumping of noble gas atoms
106:It is sometimes but inaccurately referred to as
1092:chemically-induced dynamic nuclear polarization
8:
911:{\displaystyle \nu _{0}=-\gamma B_{0}/2\pi }
692:denotes the spin operator of the a-th spin;
265:) corresponds to the indirect spin-spin, or
1358:"Atomic magnetometer is most sensitive yet"
638:denotes the gyromagnetic ratio of spin a;
1308:
1238:
1050:
1039:
1038:
1035:
1015:
994:
983:
982:
979:
958:
947:
946:
943:
923:
897:
891:
872:
866:
846:
840:
831:
829:
808:
797:
796:
793:
772:
761:
760:
757:
730:
724:
703:
697:
676:
670:
649:
643:
622:
616:
596:
572:
561:
560:
550:
539:
538:
528:
512:
487:
476:
475:
472:
449:
436:
425:
424:
414:
395:
385:
366:
355:
354:
351:
328:
317:
316:
306:
295:
294:
279:
278:
276:
249:
238:
237:
234:
214:
185:
174:
173:
170:
144:
143:
141:
1088:dissolution dynamic nuclear polarization
1465:"Zero-Field Nuclear Magnetic Resonance"
1356:Commissariat, Tushna (April 24, 2013).
1204:
598:
499:
378:
27:Acquisition of NMR spectra of chemicals
752:Importantly, the relative strength of
95:vapor cells to detect zero-field NMR.
1528:" J. Magn. Reson. (2009), 199, 25-29.
611:denotes the reduced Planck constant;
7:
1535:” Nature Physics (2011), 7, 571–575.
1508:"A Hitchhiker's Guide to ZULF NMR"
25:
1080:parahydrogen-induced polarization
1098:Excitation and spin manipulation
1506:Eills, J. (September 3, 2020).
1327:10.1103/PhysRevLett.110.160802
1059:{\displaystyle {\hat {H}}_{J}}
1044:
1003:{\displaystyle {\hat {H}}_{z}}
988:
967:{\displaystyle {\hat {H}}_{J}}
952:
847:
832:
817:{\displaystyle {\hat {H}}_{J}}
802:
781:{\displaystyle {\hat {H}}_{z}}
766:
566:
544:
481:
430:
420:
401:
360:
322:
300:
284:
258:{\displaystyle {\hat {H}}_{J}}
243:
194:{\displaystyle {\hat {H}}_{z}}
179:
149:
1:
1152:Definition of the ZULF regime
1280:10.1021/acs.analchem.0c04738
108:nuclear quadrupole resonance
1493:10.1103/PhysRevLett.50.1807
1442:10.1021/acs.jpclett.7b00349
1169:frequency matches the spin
658:{\displaystyle \sigma _{a}}
631:{\displaystyle \gamma _{a}}
1582:
1566:Nuclear magnetic resonance
1103:in a stationary state (or
158:{\displaystyle {\hat {H}}}
123:Zero-field NMR experiments
51:nuclear magnetic resonance
1146:SERF atomic magnetometers
88:SERF atomic magnetometers
1406:10.1021/acs.jpca.6b04017
1142:magnetoresistive sensors
84:magnetoresistive sensors
1296:Physical Review Letters
1167:nuclear spin precession
854:{\displaystyle |B_{0}|}
222:{\displaystyle \sigma }
71:superconducting magnets
39:Zero- to ultralow-field
1231:10.1002/anie.202006266
1161:
1120:
1060:
1024:
1004:
968:
932:
912:
855:
818:
782:
743:
742:{\displaystyle J_{ab}}
713:
686:
659:
632:
605:
604:{\displaystyle \hbar }
582:
459:
338:
259:
223:
195:
159:
119:
49:is the acquisition of
35:
1378:U.S. patent 6,919,838
1219:Angew. Chem. Int. Ed.
1159:
1113:
1061:
1025:
1005:
974:is a perturbation to
969:
933:
913:
856:
819:
783:
744:
714:
712:{\displaystyle B_{0}}
687:
685:{\displaystyle I_{a}}
660:
633:
606:
583:
460:
339:
260:
224:
201:) corresponds to the
196:
160:
116:
33:
1430:J. Phys. Chem. Lett.
1268:Analytical Chemistry
1034:
1014:
978:
942:
922:
865:
828:
792:
756:
723:
696:
669:
642:
615:
595:
471:
350:
275:
233:
229:). The second term (
213:
169:
140:
61:(including from the
1485:1983PhRvL..50.1807W
1319:2013PhRvL.110p0802S
1225:(39): 17026–17032.
75:inductive detectors
1162:
1121:
1056:
1020:
1000:
964:
928:
908:
851:
814:
778:
739:
709:
682:
655:
628:
601:
578:
523:
455:
390:
334:
255:
219:
191:
155:
120:
36:
1479:(22): 1807–1810.
1400:(25): 4343–4348.
1188:Earth's field NMR
1047:
1023:{\displaystyle J}
991:
955:
931:{\displaystyle J}
805:
769:
569:
547:
508:
484:
433:
381:
363:
325:
303:
287:
246:
182:
152:
128:Spin Hamiltonians
100:hyperpolarization
16:(Redirected from
1573:
1512:
1511:
1503:
1497:
1496:
1473:Phys. Rev. Lett.
1469:
1460:
1454:
1453:
1436:(7): 1512–1516.
1424:
1418:
1417:
1393:J. Phys. Chem. A
1387:
1381:
1380:
1374:
1368:
1367:
1353:
1347:
1346:
1312:
1290:
1284:
1283:
1274:(6): 3226–3232.
1259:
1253:
1252:
1242:
1209:
1128:Signal detection
1065:
1063:
1062:
1057:
1055:
1054:
1049:
1048:
1040:
1030:-couplings, and
1029:
1027:
1026:
1021:
1009:
1007:
1006:
1001:
999:
998:
993:
992:
984:
973:
971:
970:
965:
963:
962:
957:
956:
948:
937:
935:
934:
929:
917:
915:
914:
909:
901:
896:
895:
877:
876:
860:
858:
857:
852:
850:
845:
844:
835:
823:
821:
820:
815:
813:
812:
807:
806:
798:
787:
785:
784:
779:
777:
776:
771:
770:
762:
748:
746:
745:
740:
738:
737:
718:
716:
715:
710:
708:
707:
691:
689:
688:
683:
681:
680:
664:
662:
661:
656:
654:
653:
637:
635:
634:
629:
627:
626:
610:
608:
607:
602:
587:
585:
584:
579:
577:
576:
571:
570:
562:
555:
554:
549:
548:
540:
536:
535:
522:
492:
491:
486:
485:
477:
464:
462:
461:
456:
454:
453:
441:
440:
435:
434:
426:
419:
418:
400:
399:
389:
371:
370:
365:
364:
356:
343:
341:
340:
335:
333:
332:
327:
326:
318:
311:
310:
305:
304:
296:
289:
288:
280:
264:
262:
261:
256:
254:
253:
248:
247:
239:
228:
226:
225:
220:
200:
198:
197:
192:
190:
189:
184:
183:
175:
164:
162:
161:
156:
154:
153:
145:
21:
1581:
1580:
1576:
1575:
1574:
1572:
1571:
1570:
1556:
1555:
1542:
1521:
1519:Further reading
1516:
1515:
1505:
1504:
1500:
1467:
1462:
1461:
1457:
1426:
1425:
1421:
1389:
1388:
1384:
1376:
1375:
1371:
1355:
1354:
1350:
1292:
1291:
1287:
1261:
1260:
1256:
1211:
1210:
1206:
1201:
1184:
1154:
1130:
1117:
1100:
1072:
1037:
1032:
1031:
1012:
1011:
981:
976:
975:
945:
940:
939:
920:
919:
887:
868:
863:
862:
836:
826:
825:
795:
790:
789:
759:
754:
753:
726:
721:
720:
699:
694:
693:
672:
667:
666:
645:
640:
639:
618:
613:
612:
593:
592:
559:
537:
524:
474:
469:
468:
445:
423:
410:
391:
353:
348:
347:
315:
293:
273:
272:
269:, interaction.
236:
231:
230:
211:
210:
172:
167:
166:
138:
137:
130:
125:
59:magnetic fields
28:
23:
22:
15:
12:
11:
5:
1579:
1577:
1569:
1568:
1558:
1557:
1554:
1553:
1548:
1541:
1540:External links
1538:
1537:
1536:
1529:
1520:
1517:
1514:
1513:
1498:
1455:
1419:
1382:
1369:
1348:
1303:(16): 160802.
1285:
1254:
1203:
1202:
1200:
1197:
1196:
1195:
1190:
1183:
1180:
1153:
1150:
1129:
1126:
1115:
1099:
1096:
1071:
1068:
1053:
1046:
1043:
1019:
997:
990:
987:
961:
954:
951:
927:
907:
904:
900:
894:
890:
886:
883:
880:
875:
871:
849:
843:
839:
834:
811:
804:
801:
775:
768:
765:
736:
733:
729:
706:
702:
679:
675:
652:
648:
625:
621:
600:
575:
568:
565:
558:
553:
546:
543:
534:
531:
527:
521:
518:
515:
511:
507:
504:
501:
498:
495:
490:
483:
480:
452:
448:
444:
439:
432:
429:
422:
417:
413:
409:
406:
403:
398:
394:
388:
384:
380:
377:
374:
369:
362:
359:
331:
324:
321:
314:
309:
302:
299:
292:
286:
283:
252:
245:
242:
218:
207:chemical shift
188:
181:
178:
151:
148:
129:
126:
124:
121:
26:
24:
18:Zero Field NMR
14:
13:
10:
9:
6:
4:
3:
2:
1578:
1567:
1564:
1563:
1561:
1552:
1549:
1547:
1544:
1543:
1539:
1534:
1530:
1527:
1523:
1522:
1518:
1509:
1502:
1499:
1494:
1490:
1486:
1482:
1478:
1475:
1474:
1466:
1459:
1456:
1451:
1447:
1443:
1439:
1435:
1432:
1431:
1423:
1420:
1415:
1411:
1407:
1403:
1399:
1395:
1394:
1386:
1383:
1379:
1373:
1370:
1365:
1364:
1363:Physics World
1359:
1352:
1349:
1344:
1340:
1336:
1332:
1328:
1324:
1320:
1316:
1311:
1306:
1302:
1298:
1297:
1289:
1286:
1281:
1277:
1273:
1269:
1265:
1258:
1255:
1250:
1246:
1241:
1236:
1232:
1228:
1224:
1221:
1220:
1215:
1208:
1205:
1198:
1194:
1193:Low field NMR
1191:
1189:
1186:
1185:
1181:
1179:
1175:
1172:
1168:
1158:
1151:
1149:
1147:
1143:
1139:
1134:
1127:
1125:
1112:
1108:
1106:
1097:
1095:
1093:
1089:
1085:
1081:
1076:
1069:
1067:
1051:
1041:
1017:
995:
985:
959:
949:
925:
905:
902:
898:
892:
888:
884:
881:
878:
873:
869:
841:
837:
809:
799:
773:
763:
750:
734:
731:
727:
704:
700:
677:
673:
650:
646:
623:
619:
589:
573:
563:
556:
551:
541:
532:
529:
525:
519:
516:
513:
509:
505:
502:
496:
493:
488:
478:
466:
450:
446:
442:
437:
427:
415:
411:
407:
404:
396:
392:
386:
382:
375:
372:
367:
357:
345:
329:
319:
312:
307:
297:
290:
281:
270:
268:
250:
240:
216:
208:
204:
186:
176:
146:
135:
127:
122:
115:
111:
109:
104:
101:
96:
94:
89:
85:
81:
76:
72:
68:
64:
63:Earth's field
60:
56:
52:
48:
44:
40:
32:
19:
1501:
1476:
1471:
1458:
1433:
1428:
1422:
1397:
1391:
1385:
1372:
1361:
1351:
1300:
1294:
1288:
1271:
1267:
1257:
1222:
1217:
1207:
1176:
1163:
1135:
1131:
1122:
1101:
1077:
1073:
1070:Polarization
751:
590:
467:
346:
271:
131:
105:
97:
46:
42:
38:
37:
1066:dominates.
134:Hamiltonian
1199:References
1171:relaxation
1105:eigenstate
267:J-coupling
1310:1208.1099
1045:^
989:^
953:^
906:π
885:γ
882:−
870:ν
803:^
767:^
647:σ
620:γ
599:ℏ
567:^
557:⋅
545:^
510:∑
506:π
500:ℏ
497:−
482:^
443:⋅
431:^
412:σ
408:−
393:γ
383:∑
379:ℏ
376:−
361:^
344:, where:
323:^
301:^
285:^
244:^
217:σ
180:^
150:^
67:shielding
55:spins 1/2
1560:Category
1450:28291363
1414:27243376
1335:23679590
1249:32510813
1182:See also
93:rubidium
1481:Bibcode
1343:7559023
1315:Bibcode
1240:7540358
110:(NQR).
1448:
1412:
1341:
1333:
1247:
1237:
1144:, and
1138:SQUIDs
1090:, and
465:, and
203:Zeeman
86:, and
80:SQUIDs
1468:(PDF)
1339:S2CID
1305:arXiv
1446:PMID
1410:PMID
1331:PMID
1245:PMID
788:and
517:>
43:ZULF
1489:doi
1438:doi
1402:doi
1398:120
1323:doi
1301:110
1276:doi
1235:PMC
1227:doi
1140:),
47:NMR
1562::
1487:.
1477:50
1470:.
1444:.
1408:.
1396:.
1360:.
1337:.
1329:.
1321:.
1313:.
1299:.
1272:93
1270:.
1266:.
1243:.
1233:.
1223:59
1216:.
1094:.
1086:,
1082:,
588:.
82:,
45:)
1510:.
1495:.
1491::
1483::
1452:.
1440::
1434:8
1416:.
1404::
1366:.
1345:.
1325::
1317::
1307::
1282:.
1278::
1251:.
1229::
1116:0
1052:J
1042:H
1018:J
996:z
986:H
960:J
950:H
926:J
903:2
899:/
893:0
889:B
879:=
874:0
848:|
842:0
838:B
833:|
810:J
800:H
774:z
764:H
735:b
732:a
728:J
705:0
701:B
678:a
674:I
651:a
624:a
574:b
564:I
552:a
542:I
533:b
530:a
526:J
520:b
514:a
503:2
494:=
489:J
479:H
451:0
447:B
438:a
428:I
421:)
416:a
405:1
402:(
397:a
387:a
373:=
368:z
358:H
330:J
320:H
313:+
308:z
298:H
291:=
282:H
251:J
241:H
209:(
187:z
177:H
147:H
136:(
41:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
