by neufer » Tue Jun 30, 2020 2:32 pm
neufer wrote: ↑Tue Jun 30, 2020 1:08 pm
https://en.wikipedia.org/wiki/Scutelleridae wrote:
<<Like stink bugs, a vast majority of jewel bugs, both adults and nymphs, are also capable of releasing pungent defensive chemicals from glands located on the sides of the thorax. Typical compounds exuded by jewel bugs include alcohols, aldehydes, and esters. Nymphs and adults often exhibit clustering behavior, being found in large numbers close to each other. This behavior is thought to have an evolutionary advantage. The more individuals present in an area, the stronger the odor of the chemicals released when the bugs are threatened. If this fails, stink bugs will react to threat by flying away or dropping to the ground.>>
https://en.wikipedia.org/wiki/Helium_hydride_ion wrote:
<<
Noted as the strongest known acid, the helium hydride ion (or hydridohelium(1+) ion or helonium) is a cation with chemical formula HeH+. It consists of a helium atom bonded to a hydrogen atom, with one electron removed. Since HeH+ cannot be stored in any usable form, its chemistry must be studied by forming it in situ. HeH+ has long been conjectured since the 1970s to exist in the interstellar medium. In 1956, M. Cantwell predicted theoretically that the spectrum of vibrations of that ion should be observable in the infrared. Its first detection, in the nebula NGC 7027, (using the airborne SOFIA telescope) was reported in an article published in the journal Nature in April 2019.
HeH+ is of fundamental importance in understanding the chemistry of the early universe. This is because hydrogen and helium were almost the only types of atoms formed in Big Bang nucleosynthesis. Stars formed from the primordial material should contain HeH+, which could influence their formation and subsequent evolution. In particular, its strong dipole moment makes it relevant to the opacity of zero-metallicity stars. HeH+ is also thought to be an important constituent of the atmospheres of helium-rich white dwarfs, where it increases the opacity of the gas and causes the star to cool more slowly. Several locations had been suggested as possible places HeH+ might be detected. These included cool helium stars, H II regions, and dense planetary nebulae. HeH+ could be formed in the cooling gas behind dissociative shocks in dense interstellar clouds, such as the shocks caused by stellar winds, supernovae and outflowing material from young stars. If the speed of the shock is greater than about 90 kilometres per second, quantities large enough to detect might be formed. If detected, the emissions from HeH+ would then be useful tracers of the shock.
The helium hydride ion is formed during the decay of tritium in the molecule HT or tritium molecule (T
2 =
3H
2). Although excited by the recoil from the beta decay, the molecule remains bound together. The ion was first produced in a laboratory in 1925. It is stable in isolation, but extremely reactive, and cannot be prepared in bulk, because it would react with any other molecule with which it came into contact. Unlike the dihydrogen ion H
2+, the helium hydride ion has a permanent dipole moment, which makes its spectroscopic characterization easier. The electron density in the ion is higher around the helium nucleus than the hydrogen. 80% of the electron charge is closer to the helium nucleus than to the hydrogen nucleus. Spectroscopic detection is hampered, because one of its most prominent spectral lines, at 149.14 μm, coincides with a doublet of spectral lines belonging to the methylidyne radical ⫶CH. Unlike the helium hydride ion, the neutral helium hydride molecule HeH is not stable in the ground state. However, it does exist in an excited state as an excimer (HeH
*), and its spectrum was first observed in the mid 1980s.>>
[quote=neufer post_id=303630 time=1593522501 user_id=124483]
[quote=https://en.wikipedia.org/wiki/Scutelleridae]
<<Like stink bugs, a vast majority of jewel bugs, both adults and nymphs, are also capable of releasing pungent defensive chemicals from glands located on the sides of the thorax. Typical compounds exuded by jewel bugs include alcohols, aldehydes, and esters. Nymphs and adults often exhibit clustering behavior, being found in large numbers close to each other. This behavior is thought to have an evolutionary advantage. The more individuals present in an area, the stronger the odor of the chemicals released when the bugs are threatened. If this fails, stink bugs will react to threat by flying away or dropping to the ground.>>[/quote][/quote][quote=https://en.wikipedia.org/wiki/Helium_hydride_ion]
[float=right][img3=Spacefill model of the helium hydride ion]https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Helium-hydride-cation-3D-SF.png/800px-Helium-hydride-cation-3D-SF.png[/img3][/float]
<<[b][u][color=#FF0000]Noted as the strongest known acid, the helium hydride ion[/color][/u] (or hydridohelium(1+) ion or helonium) is a cation with chemical formula [color=#FF0000]HeH[sup]+[/sup][/color]. It consists of a helium atom bonded to a hydrogen atom, with one electron removed. Since HeH[sup]+[/sup] cannot be stored in any usable form, its chemistry must be studied by forming it in situ. [color=#0000FF]HeH[sup]+[/sup] [u]has long been conjectured since the 1970s to exist in the interstellar medium. In 1956, M. Cantwell predicted theoretically that the spectrum of vibrations of that ion should be observable in the infrared. Its first detection, in the nebula NGC 7027, (using the airborne SOFIA telescope) was reported in an article published in the journal Nature in April 2019.[/color][/u]
HeH[sup]+[/sup] is of fundamental importance in understanding the chemistry of the early universe. This is because hydrogen and helium were almost the only types of atoms formed in Big Bang nucleosynthesis. Stars formed from the primordial material should contain HeH[sup]+[/sup], which could influence their formation and subsequent evolution. In particular, its strong dipole moment makes it relevant to the opacity of zero-metallicity stars. HeH[sup]+[/sup] is also thought to be an important constituent of the atmospheres of helium-rich white dwarfs, where it increases the opacity of the gas and causes the star to cool more slowly. Several locations had been suggested as possible places HeH[sup]+[/sup] might be detected. These included cool helium stars, H II regions, and dense planetary nebulae. HeH[sup]+[/sup] could be formed in the cooling gas behind dissociative shocks in dense interstellar clouds, such as the shocks caused by stellar winds, supernovae and outflowing material from young stars. If the speed of the shock is greater than about 90 kilometres per second, quantities large enough to detect might be formed. If detected, the emissions from HeH[sup]+[/sup] would then be useful tracers of the shock.[/b]
The helium hydride ion is formed during the decay of tritium in the molecule HT or tritium molecule (T[sub]2[/sub] = [sup]3[/sup]H[sub]2[/sub]). Although excited by the recoil from the beta decay, the molecule remains bound together. The ion was first produced in a laboratory in 1925. It is stable in isolation, but extremely reactive, and cannot be prepared in bulk, because it would react with any other molecule with which it came into contact. Unlike the dihydrogen ion H[sub]2[/sub][sup]+[/sup], the helium hydride ion has a permanent dipole moment, which makes its spectroscopic characterization easier. The electron density in the ion is higher around the helium nucleus than the hydrogen. 80% of the electron charge is closer to the helium nucleus than to the hydrogen nucleus. Spectroscopic detection is hampered, because one of its most prominent spectral lines, at 149.14 μm, coincides with a doublet of spectral lines belonging to the methylidyne radical ⫶CH. Unlike the helium hydride ion, the neutral helium hydride molecule HeH is not stable in the ground state. However, it does exist in an excited state as an excimer (HeH[sup]*[/sup]), and its spectrum was first observed in the mid 1980s.>>[/quote]