Chemica/-Shift Reference 非极性溶剂: Dictionary TMS-四甲基硅烷 A chemical-shift reference is used to define the (CH3)4Si positions of the resonances in the spectrum in terms of parts-per-million, or ppm, of frequency. It is a material which is often directly added to the 极性溶剂: sample. For relatively commonly observed DSS nuclides. chemical-shift reference standards have been agreed upon as indicated. In all cases, the (CH3)4Si-CH2-CH2-CH2-SO3-Na shift of this material is defined as d=o. for some more obscure nuclides, no commonly accepted standard exists. Most modern spectrometers can perform frequency referencing operations automatically, but if highly precise chemical shifts are needed. it is still advisable to include the appropriate standard and perform the frequency THMMR referencing manually.THNMR YAN Chemical-Shift Reference Dictionary: A chemical-shift reference is used to define the positions of the resonances in the spectrum in terms of parts-per-million, or ppm, of frequency. It is a material which is often directly added to the sample. For relatively commonly observed nuclides, chemical-shift reference standards have been agreed upon as indicated. In all cases, the shift of this material is defined as d=0. For some more obscure nuclides, no commonly accepted standard exists. Most modern spectrometers can perform frequency referencing operations automatically, but if highly precise chemical shifts are needed, it is still advisable to include the appropriate standard and perform the frequency referencing manually. 非极性溶剂： TMS - 四甲基硅烷 (CH3 )4Si 极性溶剂： DSS (CH3 )4Si-CH2 -CH2 -CH2 -SO3 -Na