Photochemical Removal of SO₂ and CO₂ by 172 nm Xe₂ and 146 nm Kr₂ Excimer Lamps in N₂ or Air at Atmospheric Pressure

Abstract

This paper considers population transfer between eigenstates of a finite quantum ladder controlled by a classical electric field. Using an appropriate change of variables, we show that this setting can be set in the framework of adiabatic passage, which is known to facilitate ensemble control of quantum systems. Building on this insight, we present a mathematical proof of robustness for a control protocol-chirped pulse-practised by experimentalists to drive an ensemble of quantum systems from the ground state to the most excited state. We then propose new adiabatic control protocols using a single chirped and amplitude-shaped pulse, to robustly perform any permutation of eigenstate populations, on an ensemble of systems with unknown coupling strengths. These adiabatic control protocols are illustrated by simulations on a four-level ladder.

Novel Process of Simultaneous Removal of Nitric Oxide and Sulfur Dioxide Using a Vacuum Ultraviolet (VUV)-Activated O2/H2O/H2O2 System in A Wet VUV–Spraying Reactor

“…The byproducts NO 2 – and SO 3 2– were not found in reaction solution. Besides, according to the results of Ye et al and Tsuji et al − and the present results about SO 2 direct photolysis (as shown in Figure b), some elemental sulfur may be also produced in the reaction solution. However, it is difficult to determine its content because of its very low yield in the liquid phase and the complexity of the reaction solution.…”

“…According to the results of Tsuji’s studies − and Ye et al, NO and SO 2 may be also directly decomposed by VUV light radiation according to following eqs –. …”

“…Light-induced advanced oxidation processes have demonstrated good development prospects in the area of emission reduction of NO x and SO 2 from flue gas. ,,,,,− Several semiconductor-based photocatalytic oxidation processes have been developed for removal of NO x and SO 2 from flue gas and have exhibited good removal performance for NO x and SO 2 . ,− However, some drawbacks, such as instability and low activity of photocatalyst, low penetration of UV light in solids, and restriction of low concentrations of pollutants (photocatalytic oxidation processes can be only used for the treatment of pollutants with low concentration), hinder their industrial applications. , In recent years, several photochemical oxidation processes, such as dry VUV radiation, ,− wet UV–H 2 O 2 ,, and wet UV–Fenton­(-like) processes, ,, have been developed to remove NO x and SO 2 from flue gas. Tsuji et al − successfully used 172 nm Xe 2 and 146 nm Kr 2 excimer lamps as VUV sources to remove SO 2 , NO, and NO 2 in N 2 and air without using any expensive catalysts, which shows that VUV is an effective light source for the removal of SO 2 , NO, and NO 2 . However, Tsuji’s studies − did not consider the effect of VUV irradiation in the simultaneous presence of O 2 and H 2 O, which are the two main components of actual flue gases.…”

“…Tsuji et al − successfully used 172 nm Xe 2 and 146 nm Kr 2 excimer lamps as VUV sources to remove SO 2 , NO, and NO 2 in N 2 and air without using any expensive catalysts, which shows that VUV is an effective light source for the removal of SO 2 , NO, and NO 2 . However, Tsuji’s studies − did not consider the effect of VUV irradiation in the simultaneous presence of O 2 and H 2 O, which are the two main components of actual flue gases. Ye et al determined for the first time the key reactive oxygen species that are generated by VUV radiation in simulated flue gas (N 2 , O 2 , CO 2 , and H 2 O) and evaluated the key parameters that affect the yield of the oxidants.…”

25 W of average power at 172 nm in the vacuum ultraviolet from flat, efficient lamps driven by interlaced arrays of microcavity plasmas

“…Although the Xe 2 molecular lamp (λ = 172 nm) is the most efficient emitter available in the VUV, intensities generated by commercially-available lamps are generally restricted to 30-50 mW cm 2 , and their cylindrical geometry is not amenable to the spatially uniform irradiance of a surface. [4][5][6][7][8] To briefly summarize the status of source development in the 100-250 nm region, the dearth of inexpensive and compact, but powerful, lamps and lasers has impeded the progress of VUV photonics and its applications (such as photochemistry, photopolymerization, water purification, and surface physics).…”