The interactions between three small molecules, water (H₂O), sulfur dioxide (SO₂) and acetone ((CH₃)₂CO), with the ionic liquid (IL) 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF₄], have been determined using line of sight temperature programmed desorption (LOSTPD) from a gold surface. Multilayers of the IL were deposited by physical vapour deposition with multilayers of the small molecular species (adsorbed from the gas phase) at 90 K. LOSTPD was then carried out with the small molecular species desorbing first from the mixed multilayer, followed at higher temperatures by desorption of the IL from the gold surface. The IL had a high activation energy for desorption of 126(6) kJ mol⁻¹. Pure acetone showed a desorption activation energy of 38(2) kJ mol⁻¹, which increased to 45–61 kJ mol⁻¹ when it was pre-adsorbed below an overlying porous layer of the ionic liquid at 90 K. The stabilised acetone is thought to be associated with pores containing ionic moieties. Destabilised acetone was also observed and thought to originate from pores containing octyl chains. The quantity of stabilised acetone scaled with the amount of IL, being ≈1.1 molecules per IL ion pair. SO₂ and H₂O were co-adsorbed with the IL at 90 K leading to an intimate mixture of the two. For pure SO₂ the desorption energy was 32(2) kJ mol⁻¹, which increased to 40–52 kJ mol⁻¹ for relative concentrations up to 6 SO₂ molecules per IL ion pair. For pure water the activation energies were 49(5) kJ mol⁻¹ and 43(1) kJ mol⁻¹ for amorphous and crystalline ice respectively. When co-adsorbed with the IL the stabilisation energies were 42–49 kJ mol⁻¹, but up to 505 water molecules per IL ion pair could be stabilised to some degree. The desorption mechanisms and the reasons for these interactions are discussed.

中文翻译：

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丙酮，二氧化硫和水在低温下与1-辛基-3-甲基咪唑鎓四氟硼酸酯[OMIM] [BF ₄ ]的相互作用和稳定化

水（H ₂ O），二氧化硫（SO ₂）和丙酮（（CH ₃）₂ CO）这三个小分子与离子液体（IL）四氟硼酸1-辛基-3-甲基咪唑鎓[OMIM]之间的相互作用[BF ₄ ]是使用视线温度在金表面的程序解吸（LOSTPD）确定的。IL的多层膜是通过物理气相沉积法在90 K下与小分子物质（从气相中吸收）的多层膜沉积在一起的。然后进行LOSTPD，其中小分子物质首先从混合的多层膜中解吸，然后在较高温度下通过IL从金表面解吸。IL具有较高的解吸活化能126（6）kJ mol ^-1。纯丙酮的解吸活化能为38（2）kJ mol ^-1，当它在90 K下预先吸附在离子液体的上覆多孔层下方时，解吸活化能增加到45–61 kJ mol ^-1。被认为与含有离子部分的毛孔有关。还观察到不稳定的丙酮，并认为其起源于含有辛基链的孔。稳定丙酮的数量与IL的数量成比例，每IL离子对≈1.1个分子。SO ₂和H ₂ O在90 K下与IL共吸附，导致二者紧密混合。对于纯净的SO ₂，解吸能为32（2）kJ mol ^-1，增加到40-52 kJ mol ^-1每个IL离子对的相对浓度最高为6个SO ₂分子。对于纯净水，非晶态和晶态冰的活化能分别为49（5）kJ mol ^-1和43（1）kJ mol ^-1。当与IL共同吸附时，稳定能为42–49 kJ mol ^-1，但每个IL离子对最多可稳定505个水分子到一定程度。讨论了脱附机理和这些相互作用的原因。