Small gas-phase dianions produced by sputtering and gas flooding

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Previous experiments produced gas-phase carbon dianion clusters (C(n)(2-), n ≥ 7) via Cs+ sputtering of graphite.
• Enhanced detection sensitivity for C(n)(2-) with odd n was achieved.
• The C(5)(2-) dianion has remained elusive in previous and current investigations.

Purpose of the Study:

• To extend the production and detection of gas-phase dianion clusters.
• To investigate the formation of mixed-element dianion clusters by introducing gases like O2, N2O, and SF6 during sputtering.
• To explore dianion cluster formation on different surfaces, including SiC and Be, and with hydrocarbon vapor.

Main Methods:

• Cesium (Cs+) ion bombardment of graphite, silicon carbide (SiC), and beryllium (Be) surfaces.
• Simultaneous gas flooding with oxygen (O2, N2O), sulfur hexafluoride (SF6), or toluene (C7H8) during sputtering.
• Mass spectrometry for the detection and analysis of sputtered dianion clusters.

Main Results:

• New dianion clusters were observed: OC(n)(2-), O2C(7)(2-), SC(n)(2-), SiC(n)(2-), SiOC(n)(2-), SiO2C(n)(2-), and various C(n)H(m)(2-) and Be-containing clusters.
• The C(5)(2-) dianion was not detected, with its flux estimated to be at least 5000 times lower than C(7)(2-).
• Metastable ZrF6(2-) was observed from Cs+ sputtering of Zr with SF6 flooding.
• Abundance patterns of BeCn(2-) and SiCn(2-) showed resemblance, as did SCn(2-) and Cn(2-).

Conclusions:

• The sputtering technique, enhanced with gas flooding, effectively produces a variety of mixed-element dianion clusters.
• The C(5)(2-) dianion appears to be highly unstable or produced in extremely low quantities.
• Observed abundance patterns suggest potential similarities in cluster formation or stability mechanisms across different elemental compositions.