ISO_NWIPs-for-Ballot

ISO/NP

248

3.43 quench 249 phenomenon that occurs when a superconducting magnet cannot maintain the superconducting state 250 and the current flowing in the main coil is converted into heat, causing the liquid helium coolant around 251 the magnet to evaporate rapidly 252 3.44 253 pulse sequence 254 a series of one or more radio frequency pulses applied to the test specimen with defined timing, 255 followed by the acquisition of the FID 256 257 3.45 258 window function 259 mathematical function applied to the FID prior to FT in FT-NMR ; impacts the signal-to-noise 260 ratio, line-width, and other spectral properties 261 3.46 262 reference material for chemical shift 263 reference standard 264 chemical substance or analyte that provides the signal that is used to reference the chemical shift of an 265 NMR spectrum 266 3.47 267 reference material for qNMR 268 calibration standard 269 chemical substance or compound that provides the calibration (quantitative standard) for qNMR 270 analysis 271 3.48 272 deuterated solvent 273 solvent in which some or all of the hydrogen atoms have been replaced with deuterium 274 3.49 275 balance 276 apparatus for weighing a mass 277 Note 1 to entry: Highly accurate digital balances based on the electromagnetic force compensation principle, e.g. 278 an ultramicrobalance, are used to weigh very small quantities of a sample. 279 3.50 280 minimum weight 281 smallest quantity of sample required to weigh in order to achieve a specified relative weighing 282 accuracy 283 [see ref. 6, 9 and 13] 284 4 Principles 285 4.1 Nuclear magnetic resonance spectroscopy 286 Nuclear magnetic resonance (NMR) spectroscopy is an analytical method utilizing the phenomenon that 287 the nuclei in the atoms contained in a sample that is placed in a static magnetic field will resonate at a 288 radio frequency that is unique to each nucleus, and that radio frequency is absorbed when there is a 289 transition from a low-energy nuclear spin state to a high-energy nuclear spin state. The typical target 290 nuclei observed are 1 H, 13 C, 15 N, 19 F, 31 P, 29 Si. 291

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