Optical Fluorescence Detected from X-ray Irradiated Liquid Water

Abstract

Despite its importance, the structure and dynamics of liquid water are still poorly understood in many apsects. Here, we report on the observation of optical fluorescence upon soft X-ray irradiation of liquid water. Detection of spectrally resolved fluorescence was achieved by a combination of the liquid microjet technique and fluorescence spectroscopy. We observe a genuine liquid-phase fluorescence manifested by a broad emission band in the 170 to 340 nm (4-7 eV) photon wavelength range. In addition, another narrower emission near 300 nm can be assigned to the fluorescence of OH(A state) in the gas phase, the emitting species being formed by Auger electrons escaping from liquid water. We argue that the newly observed broad-band emission of liquid water is relevant in search of extraterrestrial life, and we also envision the observed electronejection mechanism to find application for exploring solutes at liquid-vapor interfaces.

Extreme Ultraviolet to Visible Dispersed Single Photon Detection for Highly Sensitive Sensing of Fundamental Processes in Diverse Samples

“…Processes II and III have not been observed by other techniques before. All three processes are illustrated in Figure 9 [ 45 ]. In Figure 10 , the emission intensity of these distinct processes are shown as a function of the exciting photon energy for pure water (a) and a 1 molar NaNO 3 solution (b) in the vicinity of the water and nitrogen K-shell edge, respectively.…”

“…For details, see text and Ref. [ 45 ]. Reprinted with permission from The Journal of Physical Chemistry 121, 2326.…”

X-ray induced luminescence spectroscopy for DNA damaging intermediates aided by a monochromatic synchrotron radiation

“…The yields of the 'filtered XILs' of pure water and aqueous UMP for the luminescence wavelength regions of the above mentioned 'band pass' for the center of gravities of difference optical responses, such as kC ¼ 270, 295, 340, 385, 450 and 525 nm are newly measured at X-ray energies of 370-560 eV. The origin of the luminescence for pure water at X-ray energies above 530 eV was discussed in detail but the origin below 530 eV was not known (Hans et al 2017). The 'filtered XILs' of pure water at X-ray energies below 530 eV are basically the same as those of the 'total XIL' in Figure 2.…”

“…The direct excitation of water molecules is caused by the X-ray absorption by vapor molecules. The indirect excitation is due to the impact onto the water molecules by the energetic Auger electrons emitted from the vicinity of the micro-jet surface following the excitation and ionization of oxygen K-shell electrons of liquid water (Hans et al 2017).…”

Many-electron dynamics of atomic processes studied by photon-induced fluorescence spectroscopy

“…The ability of PIFS to study threshold processes has led to the fact that recently the method has been used to study processes induced by photons in molecules, clusters, and even in liquids (Hans et al, 2017). In particular, the processes of neutral dissociation of molecules (Liebel et al, 2002;Ehresmann et al, 2004bEhresmann et al, , 2006Demekhin et al, 2010c), double photoionization of molecules (Ehresmann et al, 2003), interference phenomena of the 'lifetime-vibrational interference' type (Ehresmann et al, 2007;Demekhin et al, 2008Demekhin et al, , 2010b, resonant interatomic Coulombic decay (Knie et al, 2014;Hans et al, 2016) were investigated, and the relations for partial wave analysis were proposed (Demekhin et al, 2010a).…”