| 摘要 |
A compact, low power ambient pressure pyroelectric ionization source. The source can be constructed using a z-cut lithium niobate or lithium tantalate crystal with an attached resistive heater mounted in front of the atmospheric pressure inlet of an ion trap mass spectrometer. Positive and negative ion formation alternately results from thermally cycling the crystal over a narrow temperature range. Ionization of molecules such as 1,1,1,3,3,3-hexafluoroisopropanol or benzoic acid results in the observation of the singly deprotonated species and their clusters in the negative ion mass spectrum. Ionization of molecules such as triethylamine or triphenylamine with the source results in observation of the corresponding singly protonated species of each in the positive ion mass spectrum. The pyroelectric crystals are thermally cycled by as little as 30 K from ambient temperature. Ion formation is largely unaffected by contamination of the crystal faces. This ion source is robust.
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