The fragmentation of molecular ions in association with large inert gas clusters

Extreme ultraviolet ionization of pure He nanodroplets: Mass-correlated photoelectron imaging, Penning ionization, and electron energy-loss spectra

“…Helium nanodroplets are intriguing many-body quantum systems which feature special properties such as very low equilibrium temperature (0.38 K), superfluidity, and the ability to efficiently cool and assemble embedded species ('dopants'). Therefore pure He nanodroplets have been extensively studied using electron impact ionization [1][2][3][4][5] as well as by photoexcitation and ionization with synchrotron radiation [6][7][8][9][10][11]. Recently, timeresolved experiments have become possible using femtosecond light pulses in the extreme ultraviolet (EUV) spectral range from high-order harmonic generation [12][13][14][15].…”

“…The positive charges subsequently migrate through the He droplet by resonant hopping and eventually localize by forming He + 2 molecular ions or by ionizing a dopant if present. 1,[3][4][5] The internal energy of the newly formed ion as well as the binding energy liberated upon formation of "snowball" structures (He atoms tightly bound around the ion core) is believed to stop the chargehopping process and causes massive droplet fragmentation. Therefore, He + largely from background He atoms and He + 2 from droplets are the dominant species appearing in the mass spectra.…”

“…Therefore, pure He nanodroplets have been extensively studied using electron impact ionization [1][2][3][4][5] as well as by photoexcitation and ionization with synchrotron radiation. [6][7][8][9][10][11] Recently, time-resolved experiments have become possible using femtosecond light pulses in the extreme ultraviolet (EUV) spectral range provided by high-order harmonic generation.…”

Photoionisaton of pure and doped helium nanodroplets

“…The positive charges subsequently migrate through the He droplet by resonant hopping and eventually localize by forming He + 2 molecular ions or by ionizing a dopant if present [164,174,176,177]. The internal energy of the newly formed ion as well as the binding energy liberated upon formation of snowball structures (He atoms tightly bound around the ion core) is believed to stop the charge-hopping process and to cause massive droplet fragmentation.…”

Electron-cluster interactions

“…The fragmentation channels and their electron energy dependence have been measured (11), and theoretically analyzed (12). It is possible to manipulate and custom-tailor the fragmentation in mixed clusters such as ArNC2Ha and HeNSF6, where N > 100 (17,18).…”