An Investigation of the Non-selective Etching of Synthetic Polymers by Electrospray Droplet Impact/Secondary Ion Mass Spectrometry (EDI/SIMS)

Kenzo Hiraoka; Yuji Sakai; Hiroyuki Kubota; Satoshi Ninomiya; Stephanie Rankin-Turner

doi:10.5702/massspectrometry.A0114

An Investigation of the Non-selective Etching of Synthetic Polymers by Electrospray Droplet Impact/Secondary Ion Mass Spectrometry (EDI/SIMS)

Mass Spectrom (Tokyo). 2023;12(1):A0114. doi: 10.5702/massspectrometry.A0114. Epub 2023 Jan 31.

Authors

Kenzo Hiraoka¹, Yuji Sakai¹, Hiroyuki Kubota¹, Satoshi Ninomiya¹, Stephanie Rankin-Turner²

Affiliations

¹ Clean Energy Research Center, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan.
² Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, MD, 21205, USA.

Abstract

Among the various types of cluster secondary ion mass spectrometry (SIMS), electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) is unique due to its high ionization efficiency and non-selective atomic/molecular-level surface etching ability. In this study, EDI/SIMS was applied to the non-selective etching of synthetic polymers of polystyrene (PS) and poly(9,9-di-n-octylfluonyl-2,7diyl) (PFO) deposited on a silicon substrate. The polymers gave characteristic fragment ions and the mass spectra remained unchanged with prolonged EDI irradiation time, indicating that non-selective etching can be achieved by EDI irradiation, a finding that is consistent with our previous reports based on EDI/X-ray photoelectron spectroscopy analyses. From the irradiation time and film thickness, the etching rates for PS and PFO were roughly estimated to be 0.6 nm/min and 0.15 nm/min, respectively, under the experimental conditions that were used. After the depletion of polymer sample on the surface, ion signals originating from the exposed silicon substrate were observed. This indicates that EDI/SIMS is applicable to the analysis of the interface of multilayered films composed of organic and inorganic materials.

Keywords: EDI/SIMS; cluster SIMS; poly(9,9-di-n-octylfluonyl-2,7diyl); polystyrene.