Xps instrument

An XPS instrument (Physical Electronics, Ismaning, Germany) was used to obtain the elemental composition of the clove surface. Pieces that were approximately 4 mm × 4 mm in size and 1 mm in thickness were excised from treated and untreated cloves using a scalpel, and then freeze dried. The samples were mounted onto an XPS sample holder, and their surfaces were excited by X-ray radiation from a monochromatic Al source at photon energy of 1486.6 eV. Each sample was measured three times and the mean chemical composition was calculated. The high-energy resolution spectra were acquired with an energy analyzer operating at resolution of about 0.5 eV and a pass energy of 29 eV. The spectra were analyzed using the MultiPak V8.0 software (Ulvac-phi, Inc., Chigasaki, Japan). They were calibrated while using a C 1s peak at 284.8 eV.

We used an XPS instrument (Physical Electronics, Ismaning, Germany) to obtain the elemental composition of the outermost seed surface layer, expressed in atomic percent (at.%). Pieces were excised from the seed surface and placed onto the sample holder, which was placed inside the XPS and allowed to dry for an hour in the chamber before analysis. The samples were excited by X-ray radiation from a monochromatic Al source at a photon energy of 1486.6 eV. The area analyzed was 400 m². The take-off angle was set at 45°. XPS survey-scan spectra were acquired at a pass-energy of 187 eV using an energy step of 0.4 eV. Spectra were analyzed using the MultiPak V8.0 software (Ulvac-phi, Inc., Chigasaki, Japan). The results for untreated and treated seeds are presented as the mean values of the analyses from two or three different bean seeds, respectively.