Recently, the vacuum electrospray droplet impact (V-EDI) was developed as a cluster ion beam source in our laboratory. In this work, V-EDI was applied to polymers [polyimide (PI) and polycarbonate (PC)] and metal/polymer multilayer samples (Au/PI and Au/PC). We compared the etching performance of V-EDI with that obtained by the conventional atmospheric-pressure EDI (A-EDI). The nonselective etching was observed for organic and also inorganic samples by V-EDI as by A-EDI. Etching rates for the metal and polymer analysis by V-EDI were almost the same as those observed by A-EDI. The interlayer components were clearly observed by V-EDI for multilayer samples of Au and synthetic polymers.

Useful yield for electrospray droplet impact/secondary ion mass spectrometry was estimated. The mixtures of C60/rhodamine B and C60/Aerosol OT were used as the samples for the positive and negative mode of operations, respectively. By assuming that (i) the desorption efficiencies are about the same for C60, rhodamine B and Aerosol OT, and (ii) desorption of ionic compounds directly gives the secondary ion signals, the useful yields (i.e. total ions generated divided by the total molecules desorbed) for C60 were estimated to be ~0.1. This value should be regarded as the upper limit because the neutralization of positive and negative ions in the plume and desorption of ionic compounds as neutral species are not taken into account. Copyright © 2012 John Wiley & Sons, Ltd.

In mass spectrometry, analytes must be released in the gas phase. ere are two representative methods for the gasi cation of the condensed samples, i.e., ablation and desorption. While ablation is based on the explosion induced by the energy accumulated in the condensed matrix, desorption is a single molecular process taking place on the surface. In this paper, desorption methods for mass spectrometry developed in our laboratory: ash heating/rapid cooling, Leidenfrost phenomenon-assisted thermal desorption (LPTD), solid/solid friction, liquid/solid friction, electrospray droplet impact (EDI) ionization/desorption, and probe electrospray ionization (PESI), will be described. All the methods are concerned with the surface and interface phenomena. e concept of how to desorb less-volatility compounds from the surface will be discussed.Copyright © 2017 Dilshadbek Tursunbayevich Usmanov, Satoshi Ninomiya, Lee Chuin Chen, Subhrakanti Saha, Mridul Kanti Mandal, Yuji Sakai, Rio Takaishi, Ahsan Habib, Kenzo Hiraoka, Kentaro Yoshimura, Sen Takeda, Hiroshi Wada, and Hiroshi Nonami. is is an open access article distributed under the terms of Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.Please cite this article as: Mass Spectrom (Tokyo) 2017; 6(2): S0059 Keywords: desorption, ablation, thermal desorption, Leidenfrost phenomenon, ash heating, electrospray droplet impact ionization, probe electrospray ionization (Received September 20, 2016; Accepted January 4, 2017) RATIONALE: ABLATION VS. DESORPTION e two technical terms, ablation and desorption, should be distinguished rigorously. As shown in Fig. 1, ablation is induced by explosion of the matrix or substrate whereas desorption is a single molecular event, i.e., detachment of a single molecule from the surface. e antonym of desorption is adsorption.In matrix assisted laser desorption/ionization (MALDI), for example, the photon energy is ultimately converted to thermal energy and ablation of the matrix takes place above the critical laser power (Fig. 1(a)). In ablation, the ablated materials are mainly composed of aggregates. us the ions observed in MALDI are only a small part of materials ablated. In this respect, MALDI is more likely matrixassisted laser "ablation" ionization. In secondary ion mass spectrometry (SIMS), primary projectiles such as Ar, and (Ar) n + are used. In SIMS using atomic ion projectiles, the sputtering is caused by the cascade collisions in the sample. us the useful yield de ned as [total gas phase ions detected] divided by [total amount of sample sputtered] is rather low. e small useful yields for MALDI and SIMS (10 −5 -10) originate from the fact that photons or primary beams penetrate into the target materials leading to the sputtering of the substrate. In contrast, the useful yield for desorption-based techniques could be much higher than MALDI and SIMS if the desorbed molecules are ionized by high-e cien...