ZnO hexagonal sub-microrods have been synthesized onto glass substrates through aqueous growth method by using the thermal decomposition of an aqueous solution of equimolar zinc nitrate(Zn(NO

3

)

2

·4H

2

O) or zinc acetate(Zn(CH

3

COO)

2

·2H

2

O))with methenamine ((CH

2

)

6

N

4

) by controlling the experimental conditions. XRD patterns

SEM images have been measured

which reveals the shape of the most of the ZnO sub-microrods are hexagonal-rod with two flat faces on the two ends

but some are pair rods symmetrically grown from a center to both sides and some form radial clusters from one center. The length of the rods is from 5 μm to 8 μm

the diameter from 300 nm to 700 nm and the ratio of the length to the diameter is more than 10:1. When the growth time reaches 48 h

we found that the microrods turned into hollow microtubes with the tube-thickness in the tenth of diameter. The growth mechanism is discussed by using the growth model of cathodion ligand tetrahedron. Zn-(NO

3

)

2

dissolves and forms growth units of tetrahedron Zn-(OH)

4

under the reaction of the surface activator (CH

2

)

6

N

4

. Then the incorporation of growth units leads to the formation of the ZnO crystal lattice at the interface through a dehydration reaction (OH

-

+OH

-

H

2

O+O

2-

). The fastest of the growth speed along 0001-direction leads to the formation of the ZnO microrods. The reason of forming hollow microtubes is the face of (0001) and 0001 of ZnO rods as eroded by chemical dissolution because of its metastable state. The excitation spectra of ZnO sub-microrods show that except the intrinsic inter-band excitation shorter than 370 nm

there is a strong exciton excitation peak located at around 377

3

85 nm at room temperature. The photoluminescent spectra show that there is a wide orange-red emission peaking at about 630 nm and FWHM 250 nm with the excitation wavelength 310 nm. When the excitation is a strong 325 nm He-Cd laser

the same sample will emit a strong excition emission peaking at about 385 nm

with FWHM 16 nm and a green emission peaking at about 552 nm with FWHM 120 nm. Compared with the calculated data of these intrinsic defects with the theory of FP-LMTO

the green

orange-red and red emission peaks can be attributed to the transition of oxygen vacancies to the valence band. The studies on PL of ZnO sub-microrods after annealing showed that the excitation peak at about 384 nm disappeared

and the orange-red defect emission (peak at 630 nm) shows red shift (peak at 710 nm)

and the emission intensity increases. The excitation spectra of samples after annealing showed an enhanced exciton peak at 377 nm. It indicates that after annealing

the energy transfer from the excition to the defect center occurred.