Internal Rotations Of Methyl Pivalate By Rotational Spectroscopy

The rotational spectrum of methyl pivalate ({\it t}-BuC(O)OCH$_3$) in the ground vibrational state was observed by molecular beam-Fourier transform microwave spectroscopy. Observed spectral lines for normal species as well as five $^1$$^3$C-isotopomers were mainly assigned to the {\it b}-type rotational transitions. Some high-{\it K}$_a$ lines were found to be split and we have interpreted these splittings in terms of the internal rotation of the methyl group. Some forbidden transitions were also observed for normal species in case where {\it K}$_a$ = 2 levels were involved in the internal rotation with {\it E} state. The analysis of the observed spectra was carried out by using the XIAM program and thus determined potential barrier {\it V}$_3$ to CH$_3$ internal rotation was 5.1 kJ mol$^-$$^1$. Since gas electron diffraction study for this molecule shows the large-amplitude motion of the {\it t}-Bu group, we are observing the further spectral splittings from the rotational spectra. We are also trying to observe the $^1$$^8$O-isotopomers

ROTATIONAL SPECTRUM OF METHYL PIVALATE

The rotational spectrum of methyl pivalate ({\it t}-BuC(O)OCH$_3$) in the ground vibrational state was observed by molecular beam-Fourier transform microwave spectroscopy. Thirty b-type rotational transitions were assigned. Some high-{\it K}$_a$ lines were found to be split and we have interpreted these splittings in terms of the internal rotation of the methyl group. Some forbidden transitions were also observed in case where {\it K}$_a$ = 2 levels were involved in the internal rotation with {\it E} state. The observed spectra including the forbidden transitions were analyzed using XIAM program. Spectral assignment confirmed that the observed spectral splitting was due to the methyl rotation of the methoxy group. In comparison with the theoretical rotational constants, observed rotational constants indicated the molecule took a trans-zigzag conformation for C-C-C-O-C skeleton with {\it C}$_s$ symmetry

A Search for Interstellar Carbon Chain Alcohol HC4OH in Star-Forming Region L1527 and Dark Cloud TMC-1

We report a sensitive search for the rotational transitions of the carbon chain alcohol HC4OH in the frequency range of 21.2-46.7 GHz in the star-forming region L1527 and the dark cloud TMC-1. The motivation was laboratory detection of HC4OH by microwave spectroscopy. Despite achieving rms noise levels of several millikelvin in the antenna temperature using the 45 m telescope at Nobeyama Radio Observatory, the detection was not successful, leading to 3 sigma upper limits corresponding to the column densities of 2.0 \times 1012 and 5.6 \times 1012 cm-2 in L1527 and TMC-1, respectively. These upper limits indicate that [HC4OH]/[HC5N] ratios are less than 0.3 and 0.1 in L1527 and TMC-1, respectively, where HC5N is an HC4-chain cyanide and HC4OH is a hydroxide. These ratios suggest that the cyano carbon chain molecule dominates the hydroxyl carbon chain molecule in L1527 and TMC-1. This is contrary to the case of saturated compounds in hot cores, e.g., CH3OH and CH3CN, and can be a chemical feature of carbon chain molecules in L1527 and TMC-1. In addition, the column densities of the "unsubstituted" carbon chain molecule C4H and the sulfur-bearing molecules SO and HCS+ were determined from detected lines in L1527.Comment: Astrophysical Journal, in pres

ROTATIONAL SPECTRUM OF METHYL PIVALATE

The rotational spectrum of methyl pivalate ({\it t}-BuC(O)OCH$_3$) in the ground vibrational state was observed by molecular beam-Fourier transform microwave spectroscopy. Thirty b-type rotational transitions were assigned. Some high-{\it K}$_a$ lines were found to be split and we have interpreted these splittings in terms of the internal rotation of the methyl group. Some forbidden transitions were also observed in case where {\it K}$_a$ = 2 levels were involved in the internal rotation with {\it E} state. The observed spectra including the forbidden transitions were analyzed using XIAM program. Spectral assignment confirmed that the observed spectral splitting was due to the methyl rotation of the methoxy group. In comparison with the theoretical rotational constants, observed rotational constants indicated the molecule took a trans-zigzag conformation for C-C-C-O-C skeleton with {\it C}$_s$ symmetry

A Simple Colorimetric Method for the Evaluation of Growth and Chemosensitivity of Tumor Cells in Soft Agar Culture

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。A simple colorimetric method (color assay) was developed in order to evaluate the in vitro growth and survival of tumor cells in soft agar cultures. The assay detects the color changes in the medium caused by the accumulation of acidic metabolites at the end point of the culture. The chemosensitivity of two human tumor lines to various cytotoxic agents determined by the color assay correlated well with that determined by conventional colony count in bilayer soft agar cultures. The results suggested that the color assay can be used as a supportive method for the assessment of human tumor clonogenic assay (HTCA)

VIBRATIONAL SATELLITES IN THE ROTATIONAL SPECTRA OF ϵ\epsilon-CAPROLACTAM AND CYCLOHEXANONE OXIME

Author Institution: Department of Chemistry, Sophia University, Tokyo 102-8554, JapanThe rotational spectra of the normal and deuterated species of $\epsilon$-caprolactam and cyclohexanone oxime have been studied in the range of 26-40 GHz. The rotational and centrifugal distortion constants of these species have been obtained. Then the molecular conformations of the molecules were completely determined. Three and two types of the excited vibrational satellites were observed for $\epsilon$-caprolactam and cyclohexanone oxime, respectively. The vibrational wavenumbers have been estimated from the relative intensity measurements of the absorption lines. They are 58(15) cm$^{-1}$, 105(25) cm$^{-1}$ and 237(29) cm$^{-1}$ for $\epsilon$-caprolactam and 97(28) cm$^{-1}$ and 198(35) cm$^{-1}$ for cyclohexanone oxime (The errors in parentheses are one standard deviation). Then the assignments of the vibrational modes will be discussed by comparing the experimental and theoretical wavenumbers