Charged water droplets generated by electrospray, sonic spray, and a vibrating orifice aerosol generator (VOAG) have been studied by digital macrophotography and image charge detection mass spectrometry. Image charge detection mass spectrometry provides information on the droplet size, charge, and velocity after transmission through a capillary interface. The digital images provide the droplet size distribution before they enter the capillary. Droplets with 10-100 microm radii generated by sonic spray and VOAG are reduced to 2-3 microm radii by transmission through the capillary interface. The droplets from sonic spray and VOAG are much more highly charged than expected for random charging, and positive droplets are much more prevalent than negative. For positive mode electrospray, >99% of the detected droplets carry a positive charge, whereas for negative mode electrospray, <30% of the detected droplets carry a negative charge (i.e., >70% carry a positive charge). These observation can all be accounted for by the aerodynamic breakup of the droplets in the capillary interface. This breakup reduces the droplets to a terminal size at which point further breakup does not occur. Charge separation during droplet breakup is responsible for the relatively high charges on the sonic spray and VOAG droplets and for the preference for positively charged droplets. The charge separation can be explained using the bag mechanism for droplet breakup and the electrical bilayer at the surface of water.

The limitations of existing proposed and operational publishing models intended to replace the academic journal are briefly reviewed. Three ‘insights’ are described, the first is into the ‘means/end’ confusion of much current net‐based publishing activity, the second is that it is the purpose, not the form, that is the important aspect of the traditional academic journal model, and the third is that satisfactory net‐based publishing models need not contain a central publisher. From this new viewpoint is developed the Deconstructed Journal (DJ) model which it is suggested is a better model for network based academic publishing. It also solves some of the problems of the current model. Although the main focus of the DJ model is the replacement of the STM journal it has implications for all areas of academic journal publishing.

We describe a new approach to measuring the masses of individual macroions. The method employs a pulsed acceleration tube located between two sensitive image charge detectors. The charge and velocity of the macroion are recorded with the first image charge detector. The ion is pulse accelerated through a known voltage drop, and then the charge and velocity are remeasured using the second image charge detector. The mass of the ion is deduced from its charge and its initial and final velocities. The approach has been used to measure masses in the 10(10)-10(14) Da range with z = 10(3)-10(6) and m/z = 10(6)-10(9). It should be extendable to masses of <10(6) Da. We have used the method to determine the size and charge of water droplets transmitted through a capillary interface and an aperture interface. The droplets detected from the aperture interface are approximately 1 order of magnitude smaller in mass than those detected from the capillary interface. The droplets from both interfaces have relatively low charges, particularly with the capillary interface where they are only charged to a small fraction of the Rayleigh limit. These results suggest that the aerodynamic breakup of the droplets plays a significant role in the mechanism of electrospray ionization.

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