A series of new two-photon pumped (TPP) up-conversion
lasing dyes, named as CSPI, DPASPI, PSPI, DEASPI and HEASPI respectively,
have been synthesized. These dyes are stilbene-type chromophores end-capped
with the same acceptor group but with varied donor groups, whose different
electron-donating abilities can be ordered by 1H NMR chemical
shift data. PM3 calculations show that attaching different donors changes
the bond length alternation (BLA) and charge density distribution of the styrylpyridine
skeleton. These chromophores exhibit different two-photon up-conversion
emission behavior. Pumped by a 1064 nm, ∼40 ps mode-locked
Nd ∶ YAG laser pulses, all chromophores showed two-photon
pumped (TPP) up-conversion laser emission, but the efficiencies showed
a difference of about two orders of magnitude, ranging from an up-conversion
efficiency of 10.7% for DEASPI to 0.13% for CSPI under the same experimental
conditions. The results show that the efficiency of two-photon pumped
emission is related to the intramolecular charge transfer character of the
chromophore. The two-photon pumped lasing efficiency increases both with
decreasing BLA and with increasing intramolecular charge transfer character,
measured by the parameter Δρ1,2.
我们合成了一系列新型双光子泵浦(
TPP)上转换发光
染料,分别命名为 C
SPI、DPA
SPI、P
SPI、
DEASPI 和
HEASPI。这些
染料都是链烯型发色团,末端都有相同的受体基团,但供体基团各不相同,通过 1H NMR
化学位移数据可以确定其不同的电子供体能力。PM3 计算表明,连接不同的供体会改变
苯乙烯吡啶骨架的键长交替(B
LA)和电荷密度分布。这些发色团表现出不同的双光子上转换发射行为。在 1064 nm、∼40 ps 锁模 Nd ∶ YAG 激光脉冲的泵浦作用下,所有发色团都出现了双光子泵浦(
TPP)上转换激光发射,但效率相差约两个数量级,在相同的实验条件下,
DEASPI 的上转换效率为 10.7%,而 C
SPI 为 0.13%。结果表明,双光子泵浦发光的效率与发色团的分子内电荷转移特性有关。用参数Δρ1,2测量,双光子泵浦激光效率随着B
LA的减少和分子内电荷转移特性的增加而增加。