Sandra Brünken

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The age of dense interstellar cloud cores, where stars and planets form, is a crucial parameter in star formation and difficult to measure. Some models predict rapid collapse, whereas others predict timescales of more than one million years (ref. 3). One possible approach to determining the age is through chemical changes as cloud contraction occurs, in(More)
Using the Submillimeter Array we have detected the J = 3 − 2 and 2 − 1 rotational transitions from within the first vibrationally excited state of CO toward the extreme carbon star IRC+10216 (CW Leo). The emission remains spatially unresolved with an angular resolution of ∼ 2 and, given that the lines originate from energy levels that are ∼ 3100 K above the(More)
We present a clear detection of CH2 in absorption towards the molecular cloud complexes Sagittarius B2 and W49 N using the ISO Long Wavelength Spectrometer. These observations represent the first detection of its low excitation rotational lines in the interstellar medium. Towards Sagittarius B2, we detect both ortho and para transitions allowing a(More)
The rotational spectrum of the molecular negative ion CN(-) has been detected in the laboratory at high resolution. The four lowest transitions were observed in a low pressure glow discharge through C(2)N(2) and N(2). Conclusive evidence for the identification was provided by well-resolved nitrogen quadrupole hyperfine structure in the lowest rotational(More)
We present highly accurate laboratory measurements on the pure rotational spectrum of doubly deuterated water, D2O, in selected frequency regions from 10 GHz up to 2.7 THz. Around 140 rotational transitions in both the vibrational ground and first excited bending states (upsilon2=0,1) were measured in total, involving energy levels with unexcelled high J(More)
Protonation of methane (CH4), a rather rigid molecule well described by quantum mechanics, produces CH5(+), a prototypical floppy molecule that has eluded definitive spectroscopic description. Experimental measurement of high-resolution spectra of pure CH5(+) samples poses a formidable challenge. By applying two types of action spectroscopy predicated on(More)
The proton affinities of hydrogen and oxygen are very similar. Therefore, it has been discussed that the proton transfer from the omnipresent H(3)(+) to molecular oxygen in the near thermoneutral reaction H(3)(+) + O(2) <--> O(2)H(+) + H(2) effectively binds the interstellar oxygen in O(2)H(+). In this work, the proton transfer reaction has been(More)
The rotational spectra of thioisocyanic acid (HNCS), and its three energetic isomers (HSCN, HCNS, and HSNC) have been observed at high spectral resolution by a combination of chirped-pulse and Fabry-Pérot Fourier-transform microwave spectroscopy between 6 and 40 GHz in a pulsed-jet discharge expansion. Two isomers, thiofulminic acid (HCNS) and(More)
We report the detection of direct l-type transitions towards the protoplanetary nebula CRL 618 during a study of vibrationally excited carbon chains. The J = 8, 10, 11, 12, 13, 14 ∆J = 0 transitions of HCN in its first excited bending mode v2 = 1 were detected in absorption against the continuum of the central H ii region making use of the Effelsberg 100m(More)
We present an analysis of a global, field-free data set of the methylene radical CH2 in its X 3B1 vibronic ground state by means of a novel Euler expansion of the Hamiltonian. The data set comprises pure rotational transitions up to 2 THz obtained with microwave accuracies of 30-500 kHz as well as nu2 ground-state combination differences and pure rotational(More)