layers. These Se-Ti-Se layers consist of a plane occupied by Ti atoms that is sandwiched between similar planes of Se atoms on either side. All the Se-Ti-Se layers are weakly ac- cumulated by the van der Waals attraction along the c -axis. 1T-TiSe$_{2}$ undergoes a CDW transition into a 2 a$_{0}$ × 2 a$_{0}$ × 2 c$_{0}$ super-lattice ( a$_{0}$ = 3.54 ˚ A, c$_{0}$ = 6.00 ˚ A are lattice constants) at T$_{c}$ = 200 K [10]. We synthesized a single crystal of 1T-TiSe$_{2}$ using the self-vapor transportation method [7]. By controlling the growth temperature, we obtained sample A at 700 ◦ C and sample B at 800 ◦ C. To check the CDW phase transition, we measured the temperature dependence of the resistivity of each sample. The resistivity behavior of each sample was consistent with that described in previous reports [8]. In the STM measurements, the samples were cleaved in situ just before the approach of the STM tip toward the surface in an ultra-high vacuum at 77 K. We were able to observe atomically resolved STM images in the constant height mode with a constant sample voltage V$_{s}$ applied between the tip and the sample. The STM images of sample A and B were obtained at 84 and 6.3 K, respectively. The two color pump-probe pulse method was employed with the cleaved TiSe$_{2}$ surface using a micro optical setup with a spacial resolution of approximately 10 µm [14]. We used an optical parametric oscillator pumped by a mode locked Ti:sapphire laser (76 MHz repetition rate). The time resolution was estimated to be 200 fs. The probe energy was variable in the 1.00 to 1.77 eV range and sufficient to excite an electron beyond the CDW gap. The pump and probe pulse polarization was varied to investigate the dominant direction of the deviation of reflectivity Δ R ( t ). The sample was mounted on a helium-flow cryostat and the reflection was measured at 3K. Figure 1(a) and (b) show STM images and line profiles along unit vectors, respectively. Figure 1 shows the low symmetry structure of the electron distribution in TiSe$_{2}$ with atomic resolution in sample A. In Fig. 1(a), the bright area is the point at which many electrons are tunnelling. We observed a triangular lattice of Se atoms with a lattice constant a$_{0}$ . In addition, we saw a 2 a$_{0}$ wavelength CDW along the unit vectors. To compare the amplitude of the CDW intensity for each nesting direction, we show the line profiles of the tunnelling currents along the unit vectors a 1 , a 2 , and a 3 (Fig. 1(b)). In Fig. 1(b), there is obvious difference in CDW amplitude among each directions of the unit vector. The CDW amplitude I$_{ai}$ was specified for each magnitude and labeled in order starting with largest amplitude. In 3