New physical methods of organic compound identification using a surface ionization drift spectrometer

Дрейф-Спектрометрия: Традиционные Методы И Перспективы Развития

“…Анализ органических соединений в дрейф-спектрометрах предусматривает их ионизацию на входе приборов. При этом идентификация органических соединений осуществляется по параметрам дрейфовой подвижности ионов в воздушной среде при атмосферном давлении [57-60], в том числе, методом поверхностной ионизации органических соединений азота, фосфора, мышьяка и серы [61][62][63][64][65]. В монографии подробно описана физико-химическая теория поверхностной ионизации, разработаны высокоэффективные материалы для изготовления термоэмиттеров ионов [66][67][68][69][70], продемонстрирована возможность многопараметрического распознавания молекул в едином приборе [71,72].…”

Measuring drift mobility of organic ions using a drift diode

“…The parameters U 0 and d 0 in relation (1) depend on the space charge formed in the "thermionic emitter-ion collector" gap, which leads to the appearance of a potential minimum in this gap. How ever, the values of the ion drift mobility determined in [2] using relation (1) for two nitrogen containing organic compounds exhibited a several fold difference from the values [3,4] expected for compounds of the given type.…”

“…In practice, methods of ion drift mobility measurement provide a basis for the operation of instruments used for ecolog ical monitoring of the environment and detecting haz ardous substances [1,2]. These devices are capable of detecting and identifying trace amounts of com pounds belonging to the classes of narcotic, explosive, and toxic substances.…”

“…Previously, a new method of measurement of the drift mobility μ 0 of organic ions has been proposed [2] that is based on processing of current-voltage (I-U) characteristics of a surface ionization drift diode operating in a regime of space charge limited current. These characteristics are processed in terms of the fol lowing relation: (1) where d is the distance from a thermionic emitter to ion collector, J is the density of ion current from the emitter, U is the voltage applied to the thermionic emitter-ion collector gap, and ε 0 is the permittivity of…”

“…At the same time, relation (1) was derived [2] for a simple diode model and with neglect of the direction and magni tude of gas flow in the "thermionic emitter-ion col lector gap, while the use of parameters U 0 and d 0 phys ically implies that (i) a virtual thermionic emitter is formed that occurs at a distance of d-d 0 from the ion collector and (ii) the potential difference between this emitter and collector is U-U 0 (rather than U). Equa tions describing the I-U characteristics of vacuum diodes correspond to the well known classical law, according to which the diode current in a regime of limitation by the space charge is proportional to volt age in a power of 3/2 [6].…”