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Abstract Halide perovskites are hailed as semiconductors of the 21^stcentury. Chemical vapor deposition (CVD), a solvent‐free method, allows versatility in the growth of thin films of 3‐ and 2D organic–inorganic halide perovskites. Using CVD grown methylammonium lead iodide (MAPbI₃) films as a prototype, the impact of electron beam dosage under cryogenic conditions is evaluated. With 5 kV accelerating voltage, the dosage is varied between 50 and 50000 µC cm⁻². An optimum dosage of 35 000 µC cm⁻²results in a significant blue shift and enhancement of the photoluminescence peak. Concomitantly, a strong increase in the photocurrent is observed. A similar electron beam treatment on chlorine incorporated MAPbI₃, where chlorine is known to passivate defects, shows a blue shift in the photoluminescence without improving the photocurrent properties. Low electron beam dosage under cryogenic conditions is found to damage CVD grown 2D phenylethlyammoinum lead iodide films. Monte Carlo simulations reveal differences in electron beam interaction with 3‐ and 2D halide perovskite films. 

This second paper in a series of two describes the chirped-pulse ice apparatus that permits the detection of buffer gas cooled molecules desorbed from an energetically processed ice using broadband mm-wave rotational spectroscopy. Here, we detail the lower ice stage developed to generate ices at 4 K, which can then undergo energetic processing via UV/VUV photons or high-energy electrons and which ultimately enter the gas phase via temperature-programmed desorption (TPD). Over the course of TPD, the lower ice stage is interfaced with a buffer gas cooling cell that allows for sensitive detection via chirped-pulse rotational spectroscopy in the 60–90 GHz regime. In addition to a detailed description of the ice component of this apparatus, we show proof-of-principle experiments demonstrating the detection of H2CO products formed through irradiation of neat methanol ices or 1:1 CO + CH4 mixed ices. 

The conformer distribution of normal-propyl cyanide is investigated using broadband chirped pulse rotational spectroscopy in the millimeter-wave regime coupled with buffer gas cooling. Here we explore the relative abundances of the anti and gauche conformers following room-temperature gas-phase injection into a 25 K buffer gas cell and compare to that which is observed following temperature-programmed desorption from an ice surface, similar to the slow warm-up experienced by ice grains as they approach warmer regions within the interstellar medium. The conformer distributions observed in the gas phase from room-temperature injection are then used to determine their relative energies, an important parameter needed to interpret the isomer and conformer abundances derived from astronomical observations. We find the gauche conformer to be the most stable species by ∼97 ± 21 cm−1. We further examine the relative conformer abundances following ice desorption, which are distinct from those following the gas-phase introduction. The ratios measured off the ice correspond to a conformer temperature of ∼56 K, which is much lower than their sublimation temperature of 170 K. 

Ice Lithography (IL) is a new technique for electron beam lithography that employs conformal ices (i.e., solid phase condensed gasses) as sacrificial resist layers for lithographic processes on a variety of sample types. The completely dry in-situ processing inherent in IL allows for high precision patterning of delicate and organic surfaces such as atomic force microscope (AFM) tips and proteins. In this talk I will present an overview of the capabilities of the MU IL instrument and describe our recent work, which is centered on pushing ice species beyond water. Amorphous H2O ice is a material that has been well characterized in the astrophysics community but has received little attention from the nanotechnology field. It is a positive resist that requires large critical doses (about 2C/cm^2 for 200nm thick ice). The alcohols (ethanol, methanol and isopropanol) are attractive candidates to complement water ice. They are negative phase resists which exhibit lower critical dose (0.2C/cm^2 for 200nm thick ice) requirements than water ice. We are exploring the use of alcohol resists in conjunction with Reactive Ion Etching (RIE) for accurate modification of small, delicate, structures such as AFM tips. We are also interested in characterizing the residual material from alcohol ices after exposure to the electron beam which can be achieved through several methods including Electron Energy Loss Spectroscopy (EELS) and simulations such as the high energy chemistry program GEANT-4.