1State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 2Institute of Bio- and Nanosystems, Forschungszentrum Jülich, D-52425 Jülich, Germany 3Graduate University of the Chinese Academy of Sciences, Beijing 100049
Effect of HTS Superconductors on Homogeneity of Measurement Field in Low Field Nuclear Magnetic Resonance Detection
1State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 2Institute of Bio- and Nanosystems, Forschungszentrum Jülich, D-52425 Jülich, Germany 3Graduate University of the Chinese Academy of Sciences, Beijing 100049
In recent years, superconducting quantum interference devices (SQUIDs) have been demonstrated to be useful in the low field nuclear magnetic resonance (NMR) measurements. The high temperature superconducting (HTS) SQUID used in our experiments has a frequency-independent sensitivity of 40-50 fT/Hz1/2. When a liquid nitrogen cooled LC circuit is employed to form a tuned circuit with the SQUID, the sensitivity of the system can be further enhanced. The LC circuit consists of a capacitor and a coil made of copper wire or HTS tape, which is inductively coupled to the SQUID. However, the homogeneity of the measurement field deteriorates because of the HTS tape coil in the proximity of the sample. In contrast, the thin film SQUID with a washer area of 1 cm2 has no effect on the NMR signal. Therefore, the impairment of the measurement field homogeneity in the case of different superconducting elements nearby is discussed by examining the free induction decay signals at 9 kHz. It is found that a square superconducting film with an area of 1 cm2 may compensate for the inhomogeneity of the measurement field after the adjustment of its position.
In recent years, superconducting quantum interference devices (SQUIDs) have been demonstrated to be useful in the low field nuclear magnetic resonance (NMR) measurements. The high temperature superconducting (HTS) SQUID used in our experiments has a frequency-independent sensitivity of 40-50 fT/Hz1/2. When a liquid nitrogen cooled LC circuit is employed to form a tuned circuit with the SQUID, the sensitivity of the system can be further enhanced. The LC circuit consists of a capacitor and a coil made of copper wire or HTS tape, which is inductively coupled to the SQUID. However, the homogeneity of the measurement field deteriorates because of the HTS tape coil in the proximity of the sample. In contrast, the thin film SQUID with a washer area of 1 cm2 has no effect on the NMR signal. Therefore, the impairment of the measurement field homogeneity in the case of different superconducting elements nearby is discussed by examining the free induction decay signals at 9 kHz. It is found that a square superconducting film with an area of 1 cm2 may compensate for the inhomogeneity of the measurement field after the adjustment of its position.
DONG Hui;;ZHANG Yi;KRAUSE Hans-Joachim;XIE Xiao-Ming. Effect of HTS Superconductors on Homogeneity of Measurement Field in Low Field Nuclear Magnetic Resonance Detection[J]. 中国物理快报, 2010, 27(8): 88502-088502.
DONG Hui, , ZHANG Yi, KRAUSE Hans-Joachim, XIE Xiao-Ming. Effect of HTS Superconductors on Homogeneity of Measurement Field in Low Field Nuclear Magnetic Resonance Detection. Chin. Phys. Lett., 2010, 27(8): 88502-088502.
[1] Packard M E and Varian R 1954 Phys. Rev. 93 941 [2] Clarke J, Lee A T, Mück M and Richards P L 2006 The SQUID Handbook ed Clarke J and Braginski A I (Weinheim: Wiley-VCH) vol I$\!$I and references therein [3] Bernarding J, Buntkowsky G, Macholl S, Hartwig S, Burghoff M and Trahms L 2006 J. Am. Chem. Soc. 128 714 [4] Qiu L, Zhang Y, Krause H -J, Braginski A I, Burghoff M and Trahms L 2007 Appl. Phys. Lett. 91 072505 [5] Qiu L, Zhang Y, Krause H -J, Braginski A I and Usoskin A 2007 Rev. Sci. Instrum. 78 054701 [6] Dong H, Zhang Y, Krause H -J, Xie X, Braginski A I and Offenhäusser A 2010 J. Conf.: Phys. Series (accepted) [7] Zhang Y, Qiu L, Krause H -J, Dong H, Braginski A I and Offenhäusser A 2009 Physica C 469 1624 [8] Dong H, Zhang Y, Krause H -J, Xie X, Braginski A I and Offenhäusser A 2009 Supercond. Sci. Technol. 22 125022 [9] The superconducting coil was fabricated by European High Temperature Superconducors GmbH & Co. KG (EHTS) [10] Zhang Y, Schubert J and Wolters N 2002 Physica C 372-376 282
2010, Vol. 27 
