In this paper

the tetraethoxysilane(TEOS)precursor is hydrolyzed with ethanol as co-solvent under various concentrations of hydrochloric acid catalyzer to prepare the alkoxysilane pre-polymer solutions containing the luminescent Ru(dpp)

3

2+

complex through sol-gel process.A series of oxygen-sensing films were fabricated by spin coating of such pre-polymer solutions onto glass slides followed by aging and drying of resultant gels.The effects of acid catalyzer concentration on the micro-structures of sol-gel matrices and the micro-environments of luminescent molecules are revealed by the luminescent quenching behaviors of Ru(dpp)

3

2+

complex within such sol-gel matrices under various oxygen concentrations.It is shown that the maximum emission peak of Ru(dpp)

3

2+

in sol-gel matrices is almost independent on the acid catalyzer concentration

suggesting that very dinky change of chemical micro-circumstance around Ru(dpp)

3

2+

complex can induced.Compared in ethanol solution

the emission peak of Ru(dpp)

3

2+

in solid state exhibits a red shift for about 14nm

and the red shift for Ru(dpp)

3

2+

in sol-gel matrix is only 4nm

suggesting that such matrices are excellent dispersoid for Ru(dpp)

3

2+

complex.The quenching responses of all prepared oxygen sensors generally exhibit excellent stability

reproducibility and high signal-to-noise ratio.The sensor performances such as quenching response

Q

Stern-Volmer coefficient

K

SV

and response times(both quenching time

t

Q

and resuming time

t

R

)are improved with decreasing acid catalyzer concentrations.Since the acid catalyzer concentration has almost no effect on the chemical micro-circumstance around Ru(dpp)

3

2+

complex

it seems that these improvements of sensor performance are mainly due to faster diffusion rate of oxygen in sol-gel matrices and higher collisional probability of oxygen with Ru(dpp)

3

2+

.Two facts may contribute to such improvements:firstly

the sol-gel matrices with more open and porous structures are favored when lower concentration of acid catalyzer is used;secondly

the polar Si-OH groups that have strong interaction with oxygen may be partially replaced by negative SiO

-

that cannot absorb oxygen under lower concentration of acid catalyzer.