Measurement of Doppler effects in a cryogenic buffer-gas cell

Buffer-gas cooling is a universal cooling technique for molecules and used for various purposes. One of its ap- plications is using molecules inside a buffer-gas cell for low-temperature spectroscopy. Although a high-intensity signal is expected in the cell, complex molecular dynamics is a drawback for precise spectroscopy. In this study, we performed high-resolution absorption spectroscopy of low -J transitions in the òΠ(0, 0, 0)-˜X²Σ+(0, 0, 0) band of calcium monohydroxide (CaOH). CaOH molecules were produced by laser ablation in a copper cell and cooled to ∼5 K using helium buffer gas. We probed the Doppler effects in a buffer-gas cell by injecting counterpropagating lasers inside the cell. The time evolutions of the Doppler width and shift were simulated using a dedicated Monte Carlo simulation and compared with data

Low-J Transitions in A˜2Π(0,0,0)−X˜2Σ+(0,0,0) Band of Buffer-gas-cooled CaOH

Calcium monohydroxide radical (CaOH) is receiving an increasing amount of attention from the astrophysics community as it is expected to be present in the atmospheres of hot rocky super-Earth exoplanets as well as interstellar and circumstellar environments. Here, we report the high-resolution laboratory absorption spectroscopy on low-J transitions in A ˜ 2 Π ( 0 , 0 , 0 ) − X ˜ 2 Σ + ( 0 , 0 , 0 ) band of buffer-gas-cooled CaOH. In total, 40 transitions out of the low-J states were assigned, including 27 transitions that have not been reported in previous literature. The determined rotational constants for both ground and excited states are in excellent agreement with previous literature, and the measurement uncertainty for the absolute transition frequencies was improved by more than a factor of 3. This will aid future interstellar, circumstellar, and atmospheric identifications of CaOH. The buffer-gas-cooling method employed here is a particularly powerful method to probe low-J transitions and is easily applicable to other astrophysical molecules.</jats:p

High-resolution spectroscopy of buffer-gas-cooled phthalocyanine

For over five decades, studies in the field of chemical physics and physical chemistry have primarily aimed to understand the quantum properties of molecules. However, high-resolution rovibronic spectroscopy has been limited to relatively small and simple systems because translationally and rotationally cold samples have not been prepared in sufficiently large quantities for large and complex systems. In this study, we present high-resolution rovibronic spectroscopy results for large gas-phase molecules, namely, free-base phthalocyanine (FBPc). The findings suggest that buffer-gas cooling may be effective for large molecules introduced via laser ablation. High-resolution electronic spectroscopy, combined with other experimental and theoretical studies, will be useful in understanding the quantum properties of molecules. These findings also serve as a guide for quantum chemical calculations of large molecules

Energy-Efficient Annealing Process of Ferroelectric Hf_0.5Zr_0.5O₂ Capacitor Using Ultraviolet-LED for Green Manufacturing

Thermal annealing process plays an important role in the formation of ferroelectric phase in Hf0.5Zr0.5O2 (HZO) thin films. In this study, the annealing process of the HZO capacitors is demonstrated using ultraviolet (UV)-LED, for the first time. Since the absorptance of the HZO films with TiN electrodes is highest in UV region, the UV-LED annealing process is promising to achieve a much more energy-efficient annealing process than a conventional halogen lamp RTA method. It was experimentally confirmed that UV-LED annealing reduces the energy consumption by nearly half compared to the conventional method. The ferroelectric characteristics obtained by this method are comparable to those achieved by the halogen lamp RTA process at 400-450&#x00B0;C. Grazing incidence X-ray diffraction (GIXRD) pattern shows that no monoclinic phase is formed and only the tetragonal and orthorhombic phases are confirmed. It is also confirmed that there is the in-plane tensile stress remaining after the UV-LED annealing process, which is necessary for the formation of the ferroelectric orthorhombic phase

High-resolution spectroscopy of buffer-gas-cooled phthalocyanine

For over five decades, studies in the field of chemical physics and physical chemistry have primarily aimed to understand the quantum properties of molecules. However, high-resolution rovibronic spectroscopy has been limited to relatively small and simple systems because translationally and rotationally cold samples have not been prepared in sufficiently large quantities for large and complex systems. In this study, we present high-resolution rovibronic spectroscopy results for large gas-phase molecules, namely, free-base phthalocya-nine (FBPc). The findings suggest that buffer-gas cooling may be effective for large molecules introduced via laser ablation. High-resolution electronic spectroscopy, combined with other experimental and theoretical studies, will be useful in understanding the quantum properties of molecules. These findings also serve as a guide for quantum chemical calculations of large molecules

High-resolution spectroscopy of buffer-gas-cooled phthalocyanine

High-resolution molecular spectroscopy provides invaluable insight into the quantum properties of molecules, but high-resolution rovibronic spectroscopy has largely been limited to relatively small systems owing to the difficulty in preparing translationally and rotationally cold samples for large and complex systems. Here, the authors demonstrate that buffer-gas cooling may be an effective strategy to obtain high-resolution rovibronic spectroscopy results for large gas-phase molecules