Research lecture. Mats Larsson Stockholm University

Transcription

1 Research lecture Mats Larsson Stockholm University

2 The discovery of interstellar anions: C 6 H, C 4 H, C 3 H, C 8 H, C 5 H, CN The new results from Herschel Space Observatory The importance of H for formation of molecules in the Early Universe Results from the Cassini Huygens space mission to Titan, the largest moon of Saturn Identification of H 2 CCC as a diffuse interstellar band carrier (honest but probably failed attempt) Results on dissociative recombination of HCO +

3 The presence of anions in the interstellar medium has been discussed for a long time Long carbon chains have many vibrational degrees of freedom These vibrations can accommodate excess energy when an electrons sticks to the carbon chain Laboratory microwave spectroscopy has been important for the discovery of interstellar anions Pat Thaddeus group at Harvard University Department of Astronomy is at the forefront of this type of spectroscopy

4 Thaddeus et al. Astrophys. J. 677, 1132 (2008)

5 Astrophys. J. Lett. 664, L43 (2007) Interstellar cloud TMC 1

6 Its electronic spectrum discovered by Herzberg and Lagerqvist in 1968 C 2 has been observed in diffuse clouds in the visible region Is it possible to observe C 2?

7 Formation by electron radiative attachment: X + e X + hν Destruction by: X + hν X + e (photodetachment) H + H H 2 + e (associative detachment; Early Universe H + + H 2H (mutual neutralization)

8 Ion trap from Roland Wester s Laboratory in Innsbruck Photodetachment

9 O + hν O + e Absolute cross section measured by Wester et al. in an ion trap, JCP (2009); 5 % accuracy!

10 Double ElectroStatic Ion Ring ExperimEnt: DESIREE To be commissioned late 2011, with location in Stockholm

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12 Largest space telescope ever launched (3.5 m) It covers the wavelength range μm Bridges the gap between earlier infrared space missions and ground based radioastronomy It is remarkable that by observing the universe in a new wavelength window, which was closed to us before Herschel, we obtain a lot of new, very exciting information

13 Astron. Astrophys. 518, L110 (2010) Strong support of the gas phase route to water

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15 B Larsson et al., Astron. Astrophys. 2008

16 August 1, Molecular oxygen detected in the Orion Nebula

17 No grains for formation of H 2 H + H H 2 + e When the Universe had cooled to about z = 100, H was no longer destroyed by photodetachment

18 Kreckel, Savin et al., Science 329, 69 (2010)

19 Results

20 In the 1920s and 1930s a number of diffuse bands were discovered in addition to the sharp atomic absorption lines

21 H C C C H

22 Comparison laboratory and astronomical spectrum

23 John Maier et al. have made an honest attempt and found several bands of l C 3 H 2 to coincide with some of the Diffuse Interstellar Bands There are problems with the column density, and the community is not convinced The jury is still out, however John Maier is so far ahead of anyone else, so who will enter this area? For sure, young spectroscopists do not want to spend their careers on the DIB

24 HCO+ is second only to H3+ in astrophysical importance H3+ will have its third Royal Society Discussion Meeting in 2012, HCO+ still waits for its first The discovery of interstellar HCO+ triggered the development of gas phase ion chemistry as a model for molecule formation in interstellar space (Klemperer, Herbst, Watson, Dalgarno) Theoretical work on HCO+ has a long history of controversies. Experiments during 30 years in good agreement. We have studied HCO+ in CRYRING HCO + + e H + CO

25 Manne Siegbahn Laboratory 52 meters circumference

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28 CO (X 1 Σ + ) + H 46% CO (a 3 Π) + H 20% CO (a 3 Σ + ) + H 34%

29 Future 2011 FAIR, Darmstadt

30 ALMA soon entering an Early science phase

31 ALMA will generate a lot of new molecular data Who will do the corresponding laboratory work? The reaction dynamics of anions needs to be investigated

32 Richard Thomas Wolf Geppert Vitali Zhaunerchyk Magdalena Kaminska Erik Vigren Mathias Hamberg Iryna Kashperka Magnus af Ugglas