- Chuydn miic cua cac didn tir miic donor xudng xoing hda tri, biic xa cac photon vdi nang lugng: hv2 = Eg Ê
r:la khoang each giiia donor va acceptor
£: la hing sd dien mdi cua mdi trudng
Nang lugng lidn kd't cua cap donor - acceptor la:
E - ED + E_^ (22)
Tuong tac culong giua donor \'a acceptor lam giam nang lugng lidn ket di AE, vi the khi tai hgp D - A, photon phat ra cd nang lugng:
2
hv = E g - ( E - A E ) = E . - ( E D + E , ) + - ^ (23)
* Tdi hgp bite xq noi trong mot tdm:
Khi dugc kfch thfch, trong cac hgp chit ban din cd pha tap nhiing nguydn td vdi ldp vd didn tir 3d hoac 4f chua lap day, thudng xay ra su chuyen đi biic xa ciia cac didn tii d eac ldp vd chua lap day naỵ Nd dugc ggi la biic xa ndi trong mot t^m. Biic xa nay xay ra d mgi nhiet do: tir nhiet do thap đ'n nhiet do cao nhung d nhiet do thip thi cudng do cua dam va vach kha manh. Tuy thudc vao timg loai tam tap cd mat trong hgp chat ban din ma pho biic xa cua dac trung cho nd cd the dudi dang nhiing dam kha rdng hoac nhimg vach hep (hinh 9). Neu t^m tap nao bi anh hudng manh ciia trudng tinh the (cac nguyen td vdi ldp vd 3d chua lap day) thi pho biic xa cua nd gdm nhiing dam rdng. Néu tam tap nao bi anh hudng ft ciia trudng tinh the (cac nguyen td vdi ldp vd 4f chua lap diy) thi pho biic xa cua nd gdm nhirng vach hep.
4 A / E
6T.
6Ạ
Hinh 9 : Su chuyen rdi biic xa dac trung cho ion Mn trong ban din Cdị^ Mn^ Te
2+
2 . Xay dimg he kich thich, thu pho huynh quang, tan xa Raman tren ca sd may don sac each tur kep GDM-1000 va ky thuat lock - in
a . Md dau
Xay dung mot he kfch thfch, thu pho cd do nhay tdt. on dinh va nang suit phan giai cao la mong mudn cua nhieu phdng thi nghiem quang phọ Nhu
chiing ta da biet, cac phuong phap pho hgc laser bao gdm quang ph6 hgc Raman, huynh quang, hap thụ.. da va dang dugc iing dung rdng rai de nghidn ciiu cau tnic phan tir, hoa diu, mdi trudng nude va khf, thudc tfnh vat lieu quang dien tir ke ca vat lieu cáu tnic nanọ..Gin day, cac hieu iing phi tuyd'n phat tan sd tong va phat hoa ba b^c hai da trd thanh cdng cu quang pho de khao sat be mat vdi dac trung be mat caọ Quang phd hoa ba bac hai dugc biét den nhu mot iing cir vien noi bat nhim hieu ro hon vd tfnh chat quang cua cac cau tnic nano [17 , 18] . Ngudi ta rit cin eac he quang pho thu dugc tfn hieu yd'u, xap xi nhidu dn. Nhirng he may quang pho nhu vay ndi chung rat dit tien. Chiing tdi da nghien ciiu nang cap he may quang pho GDM - 1000 cua hang Cari-Zeiss Jena CHDC Du"c cQ thanh mot he thu quang pho sir dung ky thuat khuech dai Lock - in, cd ghep ndi xir ly sd lieu trdn may tinh. May quang pho each tir kep GDM-100 cd nang suat phan giai cao nhung phan didn tir thudc the he cQ sir dung tu ghi vdi nhan quang didn loai head - on M12FC-51 vdi viing nhay pho 400-500nm. He may nay thfch hgp vdi viec thu pho Raman kfch thfch bing laser Argon cdng suit co 3-5W lien tuc hoac den thuy ngan. Tuy nhien thu pho bing tu ghi la mot bit tien Idn khdng cdn phu hgp. Chiing tdi da thay thd' he thu pho tu ghi bing ghep ndi may tfnh cimg x'di sir dung bg khuech dai Lock-in DSP-SP830, Stanford (USA) de tang do nhay va on dinh. Mot mdto budc thfch hgp dugc ghep vao de didu khien chfnh xac gdc quay cua each tir. He thu pho mdi dugc dieu khien va thu nhap sd lieu thdng qua may tfnh dua trdn phin mem viet bing Visual Basic (VB). Nhan quang didn cQ dugc thay the bing nhan quang R-928 ciia Hamamatsu (Japan) đ md rdng x^img nhay phd. Cac phep do ban dau dugc tien hanh nhim muc dich can chinh va xac dinh che do hoat dgng. Sau khi cai tid'n thanh cong x'a thiet dat chuan cho he may quang pho mdi chiing tdi da xay dung thanh cdng mot he thu pho Raman kich thfch bing laser Argon cdng suat 0.5W. Nhd thay nhan quang didn mdi chiing tdi da cd the thu dugc phd Raman ciia chiet pham dau md kfch thfch bing laser He-Ne cdng suat 30mW. Day la mot thuan Igi Idn x'i tranh dugc phdng huynh quang trong pho Raman x'a khong phai lam lanh laser nhu khi diing laser Argon. He thu pho mdi thd hien nhieu tid'n bg trong nghien
ciiu cac pho huynh quang va pho Raman cung nhu cac pho tin hieu yeu ndi chung.