Observations of different core water cluster ions Y⁻(H₂O)_n (Y = O₂, HO_x, NO_x, CO_x) and magic number in atmospheric pressure negative corona discharge mass spectrometry

Abstract

Reliable mass spectrometry data from large water clusters Y(-)(H(2)O)(n) with various negative core ions Y(-) such as O(2)(-), HO(-), HO(2)(-), NO(2)(-), NO(3)(-), NO(3)(-)(HNO(3))(2), CO(3)(-) and HCO(4)(-) have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y(-) ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y(-)(H(2)O)(m) indicating specific thermochemical stability. Thus, Y(-)(H(2)O)(m) may correspond to the magic number or first hydrated shell in the cluster series Y(-)(H(2)O)(n). The high intensity discontinuity at HO(-)(H(2)O)(3) observed was the first mass spectrometric evidence for the specific stability of HO(-)(H(2)O)(3) as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y(-)(H(2)O)(n) observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y(-)(H(2)O)(n) is described.

Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA–MS

“…fingerprints, may get lost during the extraction and processing steps. Addressing these [21] Schilling et al, 2010 [12] 32 O 2…”

“…Sekimoto et al, 2011 [21] Schilling et al, 2010 [12] 44 SiO À Schilling et al, 2010 [12] 45 HCO 2 À Sekimoto et al, 2012 [33] 46 NO 2 À Sekimoto et al, 2011 [21] Schilling et al, 2010 [12] [21] drawbacks, several studies have shown that ambient ionization/desorption MS techniques may be an alternative method in sensing paper currency for controlled substances and drug money. [25,26] It has been shown that FAPA-MS is capable of ionizing and detecting trace amounts of organic compounds on a variety of substrates.…”

Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y⁻(HF)<i>_n</i> (Y=F, O₂) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator

“…e background spectrum (Fig. 2a) 11) although the source of the carbon atoms of CO x and HCO x ions has not been yet clari ed. e spectrum obtained in the presence of the HF supply (Fig.…”

“…11) e corona discharge experiments for generating negative atmospheric core ions Y − (Y=O 2 , HO x , NO x , CO x ) 11,12) were performed under ambient laboratory conditions in the presence of nitrogen (N 2 ), oxygen (O 2 ), water vapors (H 2 O), and minor amounts of other species, such as CO 2 and Ar. e laboratory temperature and relative humidity were 298 K and 40-70%, respectively.…”

Ionization Capabilities of Hydronium Ions and High Electric Fields Produced by Atmospheric Pressure Corona Discharge

“…3e, and m/z 126 in Fig. 3f ) and water molecules in the atmospheric pressure dri region (10 5 Pa), the inside of the ori ce hole (≈10 5 Pa) and/or adiabatic expansion in the vacuum region (270 Pa), 17) as sown in Fig. 2.…”