简介：Alightpurplishredsapphireisheattreatedinanairtightcrucible.Thesamplechangeslittleincolorafterreceivingheattreatmentat1100°C,butturnstolightblueandblueafterbeingtreatedat1200°Cand1300°C,respectively.Beforeheating,theUV-VISabsorptionspectraofthesamplearedominatedbythe551nmbroadabsorptionbandcontributedbythed-electrontransition~4A_2→~4T_2ofCr~(3+).Afterheating,theUV-VISabsorptionspectraaredominatedbythe563nmbroadabsorptionbandcontributedbytheintervalencechargetransferofFe~(2+)-Ti~(4+).ThexrayphotoelectronspectroscopytestrevealsthattheFe~(2+)andTi~(4+)ioncontentsincreasewithincreasingtemperature.ThesapphirechangingfromlightpurplishredtoblueintheheatingprocessisowingtothefactthattheFe~(2+)andTi~(4+)contentsgrowandtheintervalencechargetransferofFe~(2+)-Ti~(4+)selectivelyabsorbsUV-VISlight.

简介：Inordertodeterminetheappropriatetreatmentinterval,267patientswhounderwent3sessionsoftreatmentwithQ-switchedalexandritelaserweredividedinto4groupsaccordingtotreatmentinterval,andtheirclinicalresponseswerecompared.Amongthem,187wereaskedabouttheprocessofpigmentfading.Moreover,lightandtransmissionelectronmicroscopywereperformed.Itwasnotedthattheclinicalresponseofthe5-6monthintervalgroupwassignificantlybetterthanthatofthe3-4monthgroup,butshowednosignificantdifferencefromthatofthe7-8or≥9monthgroup.80.21%ofinvestigatedpatientsstatedthatmarkedpigmentfadingcouldnolongerbeobserved7monthsafterirradiation.4monthsafterirradiation,thedegeneratedmelanosomesandcelldebriswerestillscatteredamongcollagenfibers,scavengedgraduallybymacrophage.Inconclusion,anappropriatetreatmentintervalis5-6months.