We introduce probe-substrate distance (D_ps)-control to desorption electrospray ionization (DESI) and report a systematic investigation of key experimental parameters. Examination of voltage, flow rate, and nebulizing gas pressure suggests as D_ps decreases, the distance-dependent spray current increases, until a critical point. At the critical point the relationship inverts, and the spray current decreases as the probe moves closer to the surface due to constriction of solution flow by the nebulizing gas. D_ps control was used to explore the use of spray current as a signal for feedback positioning, while mass spectrometry imaging was performed simultaneously. Further development of this technique is expected to find application in study of structure-function relationships for clinical diagnostics, biological investigation, and materials characterization.

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我们将探针-底物距离（D _ps）-控制引入到解吸电喷雾电离（DESI）中，并报告了对关键实验参数的系统研究。对电压，流量和雾化气体压力的检查表明，随着D _ps的减小，取决于距离的喷射电流会增加，直到达到临界点。在临界点，这种关系反转，并且由于雾化气体对溶液流的限制，当探针移近表面时，喷雾电流减小。d _PS对照被用来探索使用喷雾电流作为反馈定位的信号，而质谱成像是同时进行的。预期该技术的进一步发展将在临床诊断，生物学研究和材料表征的结构-功能关系的研究中找到应用。

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