This thesis is about the study of hydrocarbons via infrared spectroscopy. Hydrocarbons play an important role in the chemistry of a variety of astronomical environments from the diffuse... Show moreThis thesis is about the study of hydrocarbons via infrared spectroscopy. Hydrocarbons play an important role in the chemistry of a variety of astronomical environments from the diffuse interstellar medium to dense hydrocarbon atmospheres of solar system bodies (e.g., planetary atmospheres of Jupiter and Saturn’s moon Titan) and exoplanets. For most astronomical objects, the determination of chemical abundances, and consequently an understanding of the chemical evolution relies upon the observation of molecular spectra. However, to date astronomical models need to make assumptions, because not all of the molecules expected have been observed. This is due, in part, to a lack of accurate spectral data, which is needed for unambiguous identification. Using a combination of high-resolution infrared experiments and/or high level ab initio calculations of vibration frequencies and ground state spectroscopic constants, the infrared spectral data of HC2H, HC4H, HC6H, HC8H, C3H4, c-C3H3+ and Dn-PAHs (polycyclic aromatic hydrocarbons, PAH) are studied and presented, in order to fill in some of the missing spectral data. Show less
This thesis presents the anharmonic infrared spectra of a series of polycyclic aromatic hydrocarbons. Comparisons and characterizations are made based on high-resolution low-temperature gas-phase... Show moreThis thesis presents the anharmonic infrared spectra of a series of polycyclic aromatic hydrocarbons. Comparisons and characterizations are made based on high-resolution low-temperature gas-phase experimental spectra. Show less
The thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants,... Show moreThe thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants, with orbital periods as long as thousands of years. The thesis is based on near-infrared observations of 1 hot Jupiter and 3 wide-orbit gas giants at high spectral resolution. The observing strategies and the analyses are unique for the two types. For the hot Jupiter, HD 209458 b, the focus is the vertical temperature structure of the atmosphere. This particular hot Jupiter was previously thought to have an atmospheric layer where the temperature increases with altitude, but we found evidence against the existence of such a layer. The three wide-orbit gas giants are all in the early stages of their lives, and we measured their rotation and found a correlation with age: The very youngest objects rotate more slowly than the slightly older (20 million years) objects. We interpret this as the initially hot and bloated exoplanets cooling down and contracting, causing them to spin-up, until the contraction slows down as they approach a radius comparable to that of Jupiter. Show less
