A Simple Method for13C CPMAS NMR Measurements under High Gas Pressures

✍ Scribed by Toshikazu Miyoshi; K. Takegoshi; Takehiko Terao

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 118 KB
• Volume: 125
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1997.1134

✦ Synopsis

Magic angle spinning (MAS) NMR is a widely used and give a required pressure was transferred into the glass tube very powerful means for studies of static and dynamic strucwhose bottom was immersed in a liquid N 2 bath. The glass tures of solid materials (1). To our knowledge, however, tube was sealed, removed from the liquid N 2 bath, and left MAS NMR has not been performed under high pressure. In over 12 h at room temperature. The error in estimation of this Communication, we present a simple method for highgas pressure which originated from an error in measuring pressure MAS (HPMAS) by which pressure at least up to the capacity around the sealing point is small, because the 7 MPa can be applied, and we show the 13 C CPMAS NMR capacity around the sealing point is very small. We coated spectra observed for polystyrene (PS) under Xe or CO 2 gas the sealed point with adhesive to reinforce the sealing point pressure.

and also to balance the glass tube. To further balance the HPMAS was performed as follows: a sealed Pyrex glass MAS spinner containing the glass tube, we packed powtube with an inner pressure of 3-7 MPa was introduced into dered glass or KBr into a MAS spinner with the sealed a Chemagnetics 7.5 mm MAS spinner with an inner diameter glass tube. Most of the MAS spinners containing the glass of 5.9 mm. The outer diameter of the glass tube is 5.85 / tube could be spun at a frequency of 4.5 kHz. Although 0.05 mm, which is well fitted to the inside wall of the spinner. we have adopted a somewhat large margin for the inner The pressure limit P max of the tube is estimated from the diameter, some glass tubes burst during measurements of formula (2) NMR spectra. Since the volume of the tube is small, however, the bursting of the glass tube caused no serious damage to the NMR probe. P max Å r 2 0 1 r 2 / 1 s,