Patent Application: US-25753708-A

Abstract:
a novel molecular alloy of o 2 and h 2 and a method of producing such a molecular alloy are provided . when subjected to high pressure and extensive x - radiation , h 2 o molecules cleaved , forming o — o and h — h bonds . in the method of the present invention , the o and h framework in ice vii was converted into a molecular alloy of o 2 and h 2 . x - ray diffraction , x - ray raman scattering , and optical raman spectroscopy demonstrate that this crystalline solid differs from previously known phases .

Description:
reference will now be made in detail to the present invention and preferred embodiments . applicants observed the x - ray and pressure - induced cleaving of h 2 o in an oxygen k - edge study with a high - pressure x - ray raman scattering ( xrs ) technique ( 5 , 17 - 19 ) that requires long exposure of moderately high energy (˜ 10 kev ) x - radiation . for oxygen bonded with hydrogen in h 2 o , the k - edge xrs spectra are dominated by a cluster of peaks around 540 ev as shown in dense water below 0 . 9 gpa , ice vi between 1 and 2 gpa , and ice vii just above 2 gpa ( fig1 ). at pressures above 2 . 5 gpa , however , x - radiation induced dramatic , irreversible changes in the xrs spectra . a distinctive , sharp peak appeared at 530 ev characteristic of o — o bonding in o 2 and grew with time , reaching a plateau after 6 hours of exposure to the incident x - ray beam ( fig1 ). the plateau intensity increased with increasing pressure , and at 15 . 3 gpa , the height of the 530 ev peak matched that of the main 540 ev multiplet . applicants observed the reaction independently at the advanced photon source ( aps ) and spring - 8 during high - pressure xrs measurements of h 2 o ( fig1 ). visually , the sample changed from colorless to light brown after the conversion ( fig2 a ). optical raman scattering ( ors ) measurements showed intense , characteristic h 2 and o 2 vibrons and a diminished h 2 o signal ( fig3 ), clearly demonstrating the dissociation of h 2 o molecules and the recombination into o 2 and h 2 molecules . the resultant o 2 and h 2 molecules did not exist in the known high pressure phases of hcp - h 2 and ε - o 2 , but formed an alloy consisting of both molecular o 2 and h 2 . to better understand this material , applicants varied x - ray energy and exposure time , interval between exposure and measurement , pressure , and temperature , and studied the samples with ors and x - ray diffraction ( xrd ). at 17 . 6 gpa after x - radiation , the oh vibrational modes around 3000 cm − 1 became diminishingly weak and exhibited a different shape in comparison to ice vii ( fig3 ), indicating that the h 2 o molecules had mostly cleaved , leaving only a minor component in the new o 2 — h 2 alloy . one can rule out the hcp - h , and ε - o 2 phases based on their characteristic ors spectra . the intense q 1 ( 1 ) h 2 molecular vibron at 4304 cm − 1 ( fig3 ) is 59 cm − 1 above the q 1 ( 1 ) of pure hcp - h 2 ( 4245 cm − 1 ) ( 20 ). the weak side peak at 4236 cm − 1 indicates a small amount (& lt ; 5 %) of h 2 in a different site or possibly in a new secondary phase . the h 2 molecular rotons : s 0 ( 0 ), s 0 ( 1 ), and s 0 ( 2 ) at 360 , 610 , and 847 cm − 1 , respectively , are characteristic of freely rotating h 2 molecules . the o 2 ors vibron frequency ( 1577 cm − 1 ) is similar to that of ε - o 2 ( 21 , 22 ), but the intense , low - frequency , librational peaks at 123 and 272 cm − 1 ) are substantially lower in frequency than the characteristic , ν l1 and ν l2 modes of ε - o 2 at 155 and 360 cm − 1 , respectively , indicating that this is not ε - o 2 . the observation of a single o 2 vibron and a predominant h 2 vibron is consistent with a new alloy conserving the o 2 : h 2 ratio of approximately 1 : 2 , i . e . ( o 2 )( h 2 ) 2 , although we cannot rule out the possibility of a minor secondary phase with a different o 2 : h 2 ratio , corresponding to the weak h 2 side peak at 4236 cm − 1 . the h 2 vibron stiffening in mixed crystals have been used extensively to reveal information on matrix isolation and intermolecular interactions of h 2 ( 23 , 24 ). the vibron turnover of pure hcp - h 2 ( 20 ) shifts to higher pressure in the mixed crystals , and the effect increases with increasing molecular fraction of other molecules such as ne , hd , and d 2 ( 23 , 24 ). in the present sample , the main h 2 vibron shows substantial stiffening , which suggests that a large amount of o 2 molecules are present ( fig3 ). the pressure shifts of the ors o 2 librational peaks and h 2 vibrons are shown in fig4 and compared with corresponding peaks of hcp - h 2 and ε - o 2 . similar pressure dependence and constant offset of ors peaks of the present alloy with respect to the pure endmembers indicates these peaks have similar origins but different matrices effects , applicants conducted xrd studies of the h 2 — o 2 alloy at beamline 16 - idb of hpcat , aps , anl . sharp powder diffraction rings indicate that the alloy is a well - crystallized solid . its diffraction pattern ( fig5 ) shows some similarity to , but does not exactly fit , ε - o 2 ( 25 - 27 ). for instance , they both have a multiplet group between 2 - 2 . 4 å , and the alloy has a doublet near 3 . 4 å where ε - o 2 has a singularly strong peak ( 25 ). at this point , it is premature to present a definitive crystal structure or unit cell based on only 10 powder xrd lines . the d - spacings of the alloy , ε - o 2 , and ice vii vary similarly with pressure implying that all have similar compressibilities ( fig6 ). once synthesized and kept at high pressure , the new phase was stable with respect to laser exposure , further x - radiation , and being stored for time intervals of over 120 days . bubbles of o 2 - h 2 gaseous mixture ( identified by ors ) were released from the solid when the pressure was reduced below 1 gpa ( fig2 b ). when these bubbles were compressed to high pressures and irradiated with x - rays again they reformed the new alloy ( fig2 d ). formation of this material has thus been approached from both directions : starting with h 2 o and with an o 2 — h 2 mixture . heated in a diamond - anvil cell , the alloy is stable up to 700 k at 15 gpa . at higher temperature , this material reverts to ice vii near melting . partial dissociation of ice vii was previously observed by lin et al . ( 28 ) in high pressure - temperature experiments of h 2 o , but the reaction conditions and products were different . at high temperature and without x - radiation lin et al . detected a minor amount of ε - o 2 ( but no h 2 ) as a result of hydrogen loss to the metal gasket . the present observation differs from the reported high - pressure study of hydrogen peroxide , h 2 o 2 , which transformed to a high - pressure phase h 2 o 2 - ii , or decomposed to h 2 o + o 2 , but did not produce any h 2 molecules ( 29 ). the present observation also differs from the previously reported ( o 2 ) 3 ( h 2 ) 4 phase at 7 . 5 - 10 gpa ( 30 ) which was unstable and combusted during x - radiation . moreover , the o 2 and h 2 ors vibrons of the ( o 2 ) 3 ( h 2 ) 4 phase agree with those of ε - o 2 and hcp - h 2 respectively and thus differ from our alloy . the kinetic stability of the new material implies that there is an energy minimum separated from ice vii by a large energy barrier . the barrier may be too high to cross by thermal excitation alone , as it has not been observed in high p - t experiments up to 1000 k ( 14 , 28 ) which is equivalent to 0 . 08 ev . the 10 kev x - rays we used provide access to a large range of local energy minimum states including both ground and trapped excited electronic states of o 2 and h 2 . it may be puzzling why this new phase was not discovered earlier in hundreds of previous xrd studies of high - pressure ices . applicants conducted a reconnaissance study using several different monochromatic x - ray energies of 9 . 687 , 9 . 886 , 14 . 414 and 33 . 678 kev . the x - ray - induced reaction in ice vii was most effective with the 9 . 687 and 9 . 886 kev x - radiation , which are absorbed readily by h 2 o , was less effective with 14 . 414 kev x - radiation , and was not observed with 33 . 678 kev high - energy x - radiations which passed through h 2 o without adequate absorption . high - pressure synchrotron xrd studies typically use high - energy x - radiation above 20 kev with short exposure times of seconds to minutes ; 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